General Adaptive Syndrome

 General adaptation syndrome (GAS) is a description of the process of how your body responds to stress. The phenomenon was first identified by a scientist named Hans Selye in 1946.

Stages of General Adaptation Syndrome 

General adaptation syndrome occurs in three stages. In each of these stages, your body reacts in different ways. The physiological changes your body goes through during this process can have a long-term negative effect.

Below are the three stages of GAS explained.2

Alarm Reaction Stage 

This is the first stage of general adaptation syndrome. During this stage, your body sends a distress signal to your brain. Your brain responds by sending a message to the body releasing hormones called glucocorticoids and adrenaline; these are also known as your “fight or flight” hormones. During the alarm reaction stage, you’ll also experience elevated blood pressure and heart rate levels. 

Resistance Stage 

The resistance stage occurs after the reaction stage. During this stage, your body tries to thwart the changes that occurred during the reaction stage employing the parasympathetic nervous system. It typically occurs when whatever was triggering your stress has stopped.

If you remain stressed, the reaction stage will persist. In the resistance stage, your body begins to lower your blood pressure and heart rate. It also reduces the amount of adrenaline and cortisol being produced.

Your body, however, remains on alert in this stage and can easily switch back to the reaction stage if the stressor persists. At this stage, your body is simply trying to recover from the shock of the alarm reaction stage. 

Exhaustion Stage 

Stress puts your body through a toll, and the exhaustion stage occurs after prolonged stress. You experience this stage after your body has gone through an extended period of stress. Here, even if the stressor persists, your body is too depleted to continue to combat it. This is the riskiest stage of general adaptation syndrome, as you are most prone to developing health conditions here.

Signs of General Adaptation Syndrome 

During each of the three stages of general adaptation syndrome, your body exhibits different signs. 

Alarm Reaction Stage 

During the reaction stage, your body reacts in the following ways. 

• Elevated blood pressure 
• Heart rate quickens 
• Pupils dilate 
• Senses become heightened 
• Skin flushes 

Resistance Stage 

If there is persistent stress, in the resistance stage your body may exhibit the following:

• Irritability 
• Poor concentration 
• Frustration 

Exhaustion Stage 

The exhaustion stage leaves your body feeling unequipped to ward off stress. You are susceptible to developing stress-related conditions at this stage. Your body might exhibit the following symptoms: 

• Anxiety 
• Cognitive difficulties
• Depression 
• Fatigue
• Insomnia

Identifying General Adaptation Syndrome 

Hans Selye, a researcher, and scientist came up with the concept of general adaptation syndrome. He used the term to define the physical changes the body goes through when it's stressed. He discovered this while experimenting on lab rats.

In his study, he noticed that the rats went through specific psychological changes during the experiment when exposed to physical stressors like extreme temperatures.3

However, many other things could also trigger stress and they include: 

• Losing a loved one 
• Getting fired from a job 
• Going through a breakup 
• Having a demanding job 
  

Stress is responsible for general adaptation syndrome occurring. Although Hans Selye has only identified physical stressors in his initial experiment, any type of stress could cause GAS to occur.

During the first stage of general adaptation syndrome, your body goes into “fight or flight” mode. This mode is essential to protect yourself during a stressful or dangerous situation. You get a burst of energy that helps you think more critically and help effectively tackle the stressful situation at hand.

Complications Associated With General Adaptation Syndrome 

While general adaptation syndrome isn’t a condition that needs to be diagnosed or treated, it’s primarily a description of what happens to your body under stress. Being in a stressful state for an extended period can cause medical complications. You could develop a host of physical and medical conditions. Some of the most common conditions that have been linked to experiencing prolonged levels of either physical or mental stress include:4

• Hypertension 
• Mood and anxiety disorders 
• Heart disease 
• Immune suppression

Managing General Adaptation Syndrome 

Finding ways to cope with prolonged stress will help prevent your body from going into the exhaustion stage. The exhaustion stage is the riskiest stage of general adaptation syndrome. During this stage, your immune system is weakened, and you are at an increased risk of developing health conditions such as high blood pressure, strokes, and heart diseases.4 

There’s no one way to manage stress. You’ll have to identify your stressors and attempt to get rid of them or minimize them. A few tested and tried techniques people have used to manage stress for centuries include: 

• Eat a balanced diet: What you eat plays a significant role in how you feel. If you fuel your body with unhealthy foods, it will be ill-equipped to handle stressful situations. 
• Exercise more regularly: Research shows that exercising regularly can help to reduce your stress levels.5If you are new to exercising or don’t like to go to the gym, taking daily walks around your neighborhood is a great way to start moving. 
• Practice breathing exercises: Taking deep and controlled breaths when in a stressful situation can help you relax and cope better. 
• Identify your triggers: The first step to managing your stress is identifying what triggers it in the first place. This could be a highly demanding job, communicating with an estranged relative, or going to a specific location. Identifying what triggers your stress can help you get rid of them. 
• Write down your feelings: Journaling is an often overlooked way of dealing with stress. Writing down your feelings and coming to terms with them can help you cope better. 

Drugs and Behaviour

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DRUGS AND BEHAVIOUR

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Drug refers to any substance, other than food, that influences motor, sensory, cognitive, or other bodily processes. Drugs generally are administered for experimental, diagnostic, or treatment purposes but also tend to be used recreationally to achieve particular effects.

In case of anxiety and depression, psychotropic drugs are generally used. 

Psychotropics are a broad category of drugs that treat many different conditions. They work by adjusting levels of brain chemicals, or neurotransmitters, like dopamine, gamma aminobutyric acid (GABA), norepinephrine, and serotonin. There are five major classes of legal psychotropic medications: anti-anxiety agents.

Dopamin

 Dopamine is a type of monoamine neurotransmitter. It's made in your brain and acts as a chemical messenger, communicating messages between nerve cells in your brain and your brain and the rest of your body. Dopamine also acts as a hormone. Dopamine is responsible for allowing you to feel pleasure, satisfaction and motivation. When you feel good that you have achieved something, it's because you have a surge of dopamine in the brain. Dopamine is responsible for allowing you to feel pleasure, satisfaction and motivation. When you feel good that you have achieved something, it’s because you have a surge of dopamine in the brain.

It’s possible, however, that you start craving more of this dopamine ‘reward’, which is caused by many pleasant experiences, including eating nice food, having sex, winning a game and earning money. Alcohol and many illegal drugs cause a surge of dopamine too, which is partly why people get addicted to them.

Dopamine also has a role to play in controlling memory, mood, sleep, learning, concentration and body movements.

Activities that make you feel good will also raise dopamine. These include exercising, meditating, having a massage and getting enough sleep. Thinking about your achievements and all the good things in your life can also help.

GABA

Gamma aminobutyric acid (GABA) is a naturally occurring amino acid that works as a neurotransmitter in your brain. Neurotransmitters function as chemical messengers. GABA is considered an inhibitory neurotransmitter because it blocks, or inhibits, certain brain signals and decreases activity in your nervous system.

It is observed that both drug addiction, as well as alcoholism, lead to a person's irresponsible behavior and their increased inclination to take unnecessary risks. Also, while under the influence of drugs and alcohol, people may fall into criminal traps and often commit acts that are socially or legally unacceptable.

The main categories are:
stimulants (e.g. cocaine)
depressants (e.g. alcohol)
opium-related painkillers (e.g. heroin)
hallucinogens (e.g. LSD)

Drugs work in body in a variety of ways. They can interfere with microorganisms (germs) that invade your body, destroy abnormal cells that cause cancer, replace deficient substances (such as hormones or vitamins), or change the way that cells work in your body.

Drug abuse is a serious factor in memory loss and a lack of concentration, which can affect aspects of your life you may not have considered. Drugs can make it hard for you to study, improve your skills at work, learn and retain new concepts, and even pay attention to what's happening around you.

Alcohol, tobacco, or drug use have long been recognized as a cause of memory loss.

Smoking harms memory by reducing the amount of oxygen that gets to the brain. Studies have shown that people who smoke find it more difficult to put faces with names than do nonsmokers. Illegal drugs can change chemicals in the brain that can make it hard to recall memories.


Alcohol and Sleep
Alcohol often is thought of as a sedative or calming drug. While alcohol may induce sleep, the quality of sleep is often fragmented during the second half of the sleep period. Alcohol increases the number of times you awaken in the later half of the night, when the alcohol's relaxing effect wears off. It prevents you from getting the deep sleep and REM sleep you need, because alcohol keeps you in the lighter stages of sleep. With continued consumption just before bedtime, alcohol's sleep-inducing effect may decrease as its disruptive effects continue or increase. The sleep disruption resulting from alcohol use may lead to daytime fatigue and sleepiness. The elderly are at particular risk for alcohol-related sleep disorders, because they achieve higher levels of alcohol in the blood and brain than do younger adults after consuming an equivalent dose. Bedtime alcohol consumption among older adults may lead to unsteadiness if walking is attempted during the night, with increased risk of falls and injuries.

Drugs and Academic achievement
Teens who abuse drugs have lower grades, a higher rate of absence from school and other activities, and an increased potential for dropping out of school. Most people who use drugs regularly don’t consistently do well in school. male student with book over face sitting against wall Studies show that marijuana, for example, affects your attention, memory, and ability to learn. Its effects can last for days or weeks after the drug wears off. So, if you are smoking marijuana daily, you are not functioning at your best. Students who smoke marijuana tend to get lower grades and are more likely to drop out of high school.

Sleep stages

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STAGES OF SLEEP

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sleep is a state of perceptual disengagement from and unresponsiveness to the environment, marked by unique physiological and behavioral processes (Carskadon & Rechtschaffen, 2011).

During wakefulness, certain neurons fire in our brain, making us aroused and alert. However, during sleep, these neural circuits are inhibited, our muscles are completely relaxed, and our body becomes completely inactive (Schwartz & Roth, 2008).

There are five different stages of sleep including both REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. The five stages make one sleep cycle which usually repeat every 90 to 110 minutes.

Stage 1 non-REM sleep marks the transition from wakefulness to sleep. This stage typically lasts less than 10 minutes and is marked by a slowing of your heartbeat, breathing, and eye movements , as well as the relaxation of your muscles.

Stage 2 non-REM sleep is a period of light sleep before you enter deeper sleep, lasts roughly 20 minutes. Stage two is characterized by further slowing of both the heartbeat and breathing, and the brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles.

Formerly known as stages 3 and 4, stage 3 (N3) is the final stage of non-REM sleep. This is the deepest period of sleep and lasts 20 to 40 minutes. Your heartbeat and breathing slow to their lowest levels, and your muscles are so relaxed that it may be hard to awaken you.

REM sleep occurs 90 minutes after sleep onset, and is a much deeper sleep than any of the three stages of non-REM sleep. REM sleep is defined by rapid eye movements and an almost complete paralysis of the body, and a tendency to dream.

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The Circadian Rhythm

But how do our bodies know when to go back and forth between these states of sleep and wakefulness? Luckily, we have all an internal clock telling us when to do so. The circadian rhythm, our 24-hour clock, operates as our sleep/wake cycle.
This body clock is located in the suprachiasmatic nucleus (SCN), a pair of distinct groups of cells located in the hypothalamus (Dubokovich, 2007). It controls the production of melatonin, a hormone that makes you sleepy, by receiving information about incoming light from the eyes (Dubokovich, 2007).
When there is less light (like at night), the SCN tells the brain to make more melatonin so you get drowsy and are able to fall asleep. After a night’s rest, melatonin levels will drop, and you will be awake for the day.

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Measurement tools

Electroencephalogram (EEG)—measures and records the brainwave activity to identify sleep stages and detect seizure activity.

∘ Electrooculogram (EOG)—records eye movements. These movements are important for identifying the different sleep stages, especially the REM stage.

∘ Electromyogram (EMG)—records muscle activity (e.g., teeth grinding and face twitches; but also, limb movements using surface EMG monitoring of limb muscles, periodic or other). Chin EMG is necessary to differentiate REM from wakefulness, limb EMG can identify periodic limb movements during sleep (PLMS).

∘ Electrocardiogram (EKG)—records the heart rate and rhythm.

∘ Pulse oximetry—monitors the oxygen saturation (SO2).

∘ Respiratory monitor—measures the respiratory effort (thoracic and abdominal). It can be of several types, including impedance, inductance, strain gauges, etc.

∘ Capnography—measures and graphically displays the inhaled and exhaled CO2 concentrations at the airway opening.

∘ Transcutaneous monitors—measure the diffusion of O2 and CO2 through the skin.

∘ Microphone—continuously records the snoring volume and kind.

∘ Video camera—continuously records video. It is useful to identify the body motion and position.

∘ Thermometer—records the core body temperature and its changes.

∘ Light intensity tolerance test—determines the influence of light intensity on sleep.

∘ Nocturnal penile tumescence test—is used to identify physiological erectile dysfunctions.

∘ Nasal and oral airflow sensor—records the airflow and the breathing rate.

∘ Blood pressure monitor—measures the blood pressure and its changes.

Neural and synaptic activity

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NEURAL SYNAPTIC ACTIVITY

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Synapse: In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.

Neurotransmitters are often referred to as the body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles. Communication between two neurons happens in the synaptic cleft (the small gap between the synapses of neurons). Here, electrical signals that have travelled along the axon are briefly converted into chemical ones through the release of neurotransmitters, causing a specific response in the receiving neuron.

A neurotransmitter influences a neuron in one of three ways: excitatory, inhibitory or modulatory.

Key neurotransmitters
Acetylcholine, Glutamate , Dopamine, Noradrenaline (or norepinephrine), Histamine,.

Brain and Behaviour

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BRAIN AND BEHAVIOUR

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Behaviour is controlled by brain.

Brain: The brain is one of the largest and most complex organs in the human body.
It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses.

Lobes:
Frontal lobe: The frontal lobes are important for voluntary movement, expressive language and for managing higher level executive functions. Executive functions refer to a collection of cognitive skills including the capacity to plan, organise, initiate, self-monitor and control one's responses in order to achieve a goal.

Parietal lobe: It sits near the upper back portion of the skull, close to the parietal bone.
In the brain, the parietal lobe is located behind the frontal lobe. The parietal lobe relies heavily on many other areas of the body to receive information. For example, the skin and nerves in the skin play a large part in detecting sensory information and delivering it to the parietal lobe.

Temporal lobe: The temporal lobe is one of the four major lobes of the cerebral cortex. It is the lower lobe of the cortex, sitting close to ear level within the skull. The temporal lobe is largely responsible for creating and preserving both conscious and long-term memory.

Occipital lobe: The occipital lobe is the smallest of the four lobes of the cerebral hemisphere. It is present posterior to the parietal and temporal lobes.
The occipital lobe is primarily responsible for visual processing. 


Brain localization: Brain localization refers to the association of psychological functions with particular structures in the brain. Three techniques
provide the bulk of localization data: single-cell recording studies,lesion studies, and functional imaging studies.

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BRAIN LOCALIZATION

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Localisation of function is the idea that certain functions (e.g. language, memory, etc.) have certain locations or areas within the brain.

Motor Area
The motor area is located in the frontal lobe and is responsible for voluntary movements by sending signals to the muscles in the body.







Somatosensory Area
The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature, etc. Different parts of the somatosensory area receive messages from different locations of the body. Robertson (1995) found that this area of the brain is highly adaptable, with Braille readers having larger areas in the somatosensory area for their fingertips compared to normal sighted participants.

Visual Area
At the back of the brain, in the occipital lobe is the visual area, which receives and processes visual information. Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right hemisphere. The visual area contains different parts that process different types of information including colour, shape or movement.  

Auditory Area
The auditory area is located in the temporal lobe and is responsible for analysing and processing acoustic information. Information from the left ear goes primarily to the right hemisphere and information from the right ear goes primarily to the left hemisphere.  The auditory area contains different parts, and the primary auditory area is involved in processing simple features of sound, including volume, tempo and pitch.

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BRAIN LATERALIZATION

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What is Brain Lateralization?

Information that enters the left hemisphere travel across the corpus callosum going to the right side of the brain and vice versa. The two hemispheres of the brain (right and left hemisphere) function interdependently. lateralization refers only to the function of one structure divided between two hemispheres.

Language: Broca's area and Wernicke's area, associated with the production of speech and comprehension of speech, respectively, are located in the left cerebral hemisphere for about 95% of right-handers but about 70% of left-handers.

Hemispheric dominance: It is the theory about left-brain versus right-brain dominance is the theory that one side of the brain dominates your thinking. ... Right-brain dominant people are supposedly more curious, spontaneous and emotional while left-brained people are smart, logical and organised.
If you're mostly analytical and methodical in your thinking, you're said to be left-brained. If you tend to be more creative or artistic, you're thought to be right-brained.

Biological basis of Human behaviour

 KEYWORDS

Ref: https://www.bricefoundation.org/single-post/2016/05/06/genes-and-environmentals-effect-on-a-persons-behavior

1. Heredity : Heredity is the sum of all biological processes by which particular characteristics are transmitted from parents to their offspring. Heredity depends upon the character of the genes contained in the parents' chromosomes, which in turn depends on the particular genetic code carried by the DNA of which the chromosomes are composed.

2. Chromosomes: Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. They play a vital role in cell division, heredity, variation, mutation, repair and regeneration. Whether you are male or female, you will inherit one X chromosome from your mother; all genes on that chromosome come from her. Your gender is ultimately determined by your father, who has both an X and a Y chromosome and could contribute either of them. That's why genes on the Y chromosome are passed down only in the male line. The only way you can inherit and pass on a Y chromosome is if you are male.

3. DNA: Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). DNA is pivotal to our growth, reproduction, and health. It contains the instructions necessary for your cells to produce proteins that affect many different processes and functions in your body. Because DNA is so important, damage or mutations can sometimes contribute to the development of disease.

4. Gene: the basic unit of heredity, responsible for storing genetic information and transmitting it to subsequent generations.

5. Genotype: Genotype is the genes inside the cells, while your phenotype is the physical traits that are visible and influenced by both the genes and environment.

6. Genetic psychology: Genetic psychology is a field of study exploring how genes influence personality. Genetic psychologists typically conduct research on how specific genes influence human behavior and personality.

Psychology and Heredity
Intelligence: It is the ability to learn, reason and solve problems. Intelligence is highly heritable and predicts important educational, occupational and health outcomes better than any other trait. Recent genome-wide association studies have successfully identified inherited genome sequence differences that account for 20% of the 50% heritability of intelligence.

Personality : Personality is not determined by any single gene, but rather by the actions of many genes working together. ... Overall, genetics has more influence than parents do on shaping our personality. Molecular genetics is the study of which genes are associated with which personality traits.

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BRAIN AND BEHAVIOUR

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Behaviour is controlled by brain.

Brain: The brain is one of the largest and most complex organs in the human body.
It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses.

Lobes:
Frontal lobe: The frontal lobes are important for voluntary movement, expressive language and for managing higher level executive functions. Executive functions refer to a collection of cognitive skills including the capacity to plan, organise, initiate, self-monitor and control one's responses in order to achieve a goal.

Parietal lobe: It sits near the upper back portion of the skull, close to the parietal bone.
In the brain, the parietal lobe is located behind the frontal lobe. The parietal lobe relies heavily on many other areas of the body to receive information. For example, the skin and nerves in the skin play a large part in detecting sensory information and delivering it to the parietal lobe.

Temporal lobe: The temporal lobe is one of the four major lobes of the cerebral cortex. It is the lower lobe of the cortex, sitting close to ear level within the skull. The temporal lobe is largely responsible for creating and preserving both conscious and long-term memory.

Occipital lobe: The occipital lobe is the smallest of the four lobes of the cerebral hemisphere. It is present posterior to the parietal and temporal lobes.
The occipital lobe is primarily responsible for visual processing. 


Brain localization: Brain localization refers to the association of psychological functions with particular structures in the brain. Three techniques
provide the bulk of localization data: single-cell recording studies,lesion studies, and functional imaging studies.

===========================================================================

BRAIN LOCALIZATION

==========================================================================

Localisation of function is the idea that certain functions (e.g. language, memory, etc.) have certain locations or areas within the brain.

Motor Area
The motor area is located in the frontal lobe and is responsible for voluntary movements by sending signals to the muscles in the body.







Somatosensory Area
The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature, etc. Different parts of the somatosensory area receive messages from different locations of the body. Robertson (1995) found that this area of the brain is highly adaptable, with Braille readers having larger areas in the somatosensory area for their fingertips compared to normal sighted participants.

Visual Area
At the back of the brain, in the occipital lobe is the visual area, which receives and processes visual information. Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right hemisphere. The visual area contains different parts that process different types of information including colour, shape or movement.  

Auditory Area
The auditory area is located in the temporal lobe and is responsible for analysing and processing acoustic information. Information from the left ear goes primarily to the right hemisphere and information from the right ear goes primarily to the left hemisphere.  The auditory area contains different parts, and the primary auditory area is involved in processing simple features of sound, including volume, tempo and pitch.

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BRAIN LATERALIZATION

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What is Brain Lateralization?

Information that enters the left hemisphere travel across the corpus callosum going to the right side of the brain and vice versa. The two hemispheres of the brain (right and left hemisphere) function interdependently. lateralization refers only to the function of one structure divided between two hemispheres.

Language: Broca's area and Wernicke's area, associated with the production of speech and comprehension of speech, respectively, are located in the left cerebral hemisphere for about 95% of right-handers but about 70% of left-handers.

Hemispheric dominance: It is the theory about left-brain versus right-brain dominance is the theory that one side of the brain dominates your thinking. ... Right-brain dominant people are supposedly more curious, spontaneous and emotional while left-brained people are smart, logical and organised.
If you're mostly analytical and methodical in your thinking, you're said to be left-brained. If you tend to be more creative or artistic, you're thought to be right-brained.

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NEURAL SYNAPTIC ACTIVITY

=============================================================================

Synapse: In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.

Neurotransmitters are often referred to as the body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles. Communication between two neurons happens in the synaptic cleft (the small gap between the synapses of neurons). Here, electrical signals that have travelled along the axon are briefly converted into chemical ones through the release of neurotransmitters, causing a specific response in the receiving neuron.

A neurotransmitter influences a neuron in one of three ways: excitatory, inhibitory or modulatory.

Key neurotransmitters
Acetylcholine, Glutamate , Dopamine, Noradrenaline (or norepinephrine), Histamine,.

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ENDOCRINE GLAND AND STRESS

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. Hormones Definition
“Hormones are chemicals synthesized and produced by the specialized glands to control and regulate the activity of certain cells and organs. These specialized glands are known as endocrine glands.”

2. Types: To regulate various functions, different types of hormones are produced in the body. They are classified as follows: Peptide Hormones and
Steroid Hormones.

3. Peptide Hormones: Peptide hormones are composed of amino acids and are soluble in water.

4. Steroid Hormones: Steroid hormones are fat-soluble and are able to pass through a cell membrane. Sex hormones such as testosterone, estrogen and progesterone are examples of steroid hormones.

5. Endocrine glands: Hormones are released by the endocrine glands. These are different from other glands of the human body as they are ductless.

6. Ductless gland - Ductless gland is any of the glands of the endocrine system that secrete hormones directly into the bloodstream.

7. Endocrine system: The endocrine system works to regulate certain internal processes. (Note: endocrine shouldn’t be confused with exocrine. Exocrine glands, such as sweat and salivary glands, secrete externally and internally via ducts. Endocrine glands secrete hormones internally, using the bloodstream.)

The endocrine system helps control the following processes and systems:
Growth and development
Homeostasis (the internal balance of body systems)
Metabolism (body energy levels)
Reproduction
Response to stimuli (stress and/or injury)

Glands
Hypothalamus: It controls the body temperature, regulates emotions, hunger, thirst, sleep, moods and allow the production of hormones.
Pineal: Pineal is also known as the thalamus. It produces serotonin derivatives of melatonin, which affects sleep patterns.

Hypothalamus 

hypothalamus, a structure deep in your brain, acts as your body's smart control coordinating center. Its main function is to keep your body in a stable state called homeostasis. It does its job by directly influencing your autonomic nervous system or by managing hormones.

Thymus: The thymus makes white blood cells called T lymphocytes (also called T cells). These are an important part of the body's immune system, which helps us to fight infection. The thymus produces all our T cells before we become teenagers.

Parathyroid: This gland helps in controlling the amount of calcium present in the body.
Thymus: It helps in the production of T-cells, functioning of the adaptive immune system and maturity of the thymus.
Thyroid: It produces hormones that affect the heart rate and how calories are burnt.
Adrenal: This gland produces the hormones that control the sex drive, cortisol and stress hormone.
Pituitary: It is also termed as the “master control gland,”. This is because the pituitary gland helps in controlling other glands. Moreover, it develops the hormones that trigger growth and development.
Pancreas: This gland is involved in the production of insulin hormones, which plays a crucial role in maintaining blood sugar levels.
Testes: In men, the testes secrete the male sex hormone, testosterone. It also produces sperm.
Ovaries: In the female reproductive system, the ovaries release estrogen, progesterone, testosterone and other female sex hormones.
All these glands work together to produce and manage the hormones of the body.

Hormones:
List of Important Hormones
Cortisol – It has been named as the “stress hormone” as it helps the body in responding to stress. This is done by increasing the heart rate, elevating blood sugar levels etc.
Estrogen-This is the main sex hormone present in women which bring about puberty, prepares the uterus and body for pregnancy and even regulates the menstrual cycle. Estrogen level changes during menopause because of which women experience many uncomfortable symptoms.
Melatonin – It primarily controls the circadian rhythm or sleep cycles.
Progesterone – It is a female sex hormone also responsible for menstrual cycle, pregnancy and embryogenesis.
Testosterone – This is the most important sex hormone synthesized in men, which cause puberty, muscle mass growth, and strengthen the bones and muscles, increase bone density and controls facial hair growth.

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STAGES OF SLEEP

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sleep is a state of perceptual disengagement from and unresponsiveness to the environment, marked by unique physiological and behavioral processes (Carskadon & Rechtschaffen, 2011).

During wakefulness, certain neurons fire in our brain, making us aroused and alert. However, during sleep, these neural circuits are inhibited, our muscles are completely relaxed, and our body becomes completely inactive (Schwartz & Roth, 2008).

There are five different stages of sleep including both REM (rapid eye movement) and NREM (non-rapid eye movement) sleep. The five stages make one sleep cycle which usually repeat every 90 to 110 minutes.

Stage 1 non-REM sleep marks the transition from wakefulness to sleep. This stage typically lasts less than 10 minutes and is marked by a slowing of your heartbeat, breathing, and eye movements , as well as the relaxation of your muscles.

Stage 2 non-REM sleep is a period of light sleep before you enter deeper sleep, lasts roughly 20 minutes. Stage two is characterized by further slowing of both the heartbeat and breathing, and the brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles.

Formerly known as stages 3 and 4, stage 3 (N3) is the final stage of non-REM sleep. This is the deepest period of sleep and lasts 20 to 40 minutes. Your heartbeat and breathing slow to their lowest levels, and your muscles are so relaxed that it may be hard to awaken you.

REM sleep occurs 90 minutes after sleep onset, and is a much deeper sleep than any of the three stages of non-REM sleep. REM sleep is defined by rapid eye movements and an almost complete paralysis of the body, and a tendency to dream.

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The Circadian Rhythm

But how do our bodies know when to go back and forth between these states of sleep and wakefulness? Luckily, we have all an internal clock telling us when to do so. The circadian rhythm, our 24-hour clock, operates as our sleep/wake cycle.
This body clock is located in the suprachiasmatic nucleus (SCN), a pair of distinct groups of cells located in the hypothalamus (Dubokovich, 2007). It controls the production of melatonin, a hormone that makes you sleepy, by receiving information about incoming light from the eyes (Dubokovich, 2007).
When there is less light (like at night), the SCN tells the brain to make more melatonin so you get drowsy and are able to fall asleep. After a night’s rest, melatonin levels will drop, and you will be awake for the day.

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Measurement tools

Electroencephalogram (EEG)—measures and records the brainwave activity to identify sleep stages and detect seizure activity.

∘ Electrooculogram (EOG)—records eye movements. These movements are important for identifying the different sleep stages, especially the REM stage.

∘ Electromyogram (EMG)—records muscle activity (e.g., teeth grinding and face twitches; but also, limb movements using surface EMG monitoring of limb muscles, periodic or other). Chin EMG is necessary to differentiate REM from wakefulness, limb EMG can identify periodic limb movements during sleep (PLMS).

∘ Electrocardiogram (EKG)—records the heart rate and rhythm.

∘ Pulse oximetry—monitors the oxygen saturation (SO2).

∘ Respiratory monitor—measures the respiratory effort (thoracic and abdominal). It can be of several types, including impedance, inductance, strain gauges, etc.

∘ Capnography—measures and graphically displays the inhaled and exhaled CO2 concentrations at the airway opening.

∘ Transcutaneous monitors—measure the diffusion of O2 and CO2 through the skin.

∘ Microphone—continuously records the snoring volume and kind.

∘ Video camera—continuously records video. It is useful to identify the body motion and position.

∘ Thermometer—records the core body temperature and its changes.

∘ Light intensity tolerance test—determines the influence of light intensity on sleep.

∘ Nocturnal penile tumescence test—is used to identify physiological erectile dysfunctions.

∘ Nasal and oral airflow sensor—records the airflow and the breathing rate.

∘ Blood pressure monitor—measures the blood pressure and its changes.

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DRUGS AND BEHAVIOUR

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Drug refers to any substance, other than food, that influences motor, sensory, cognitive, or other bodily processes. Drugs generally are administered for experimental, diagnostic, or treatment purposes but also tend to be used recreationally to achieve particular effects.

In case of anxiety and depression, psychotropic drugs are generally used. 

Psychotropics are a broad category of drugs that treat many different conditions. They work by adjusting levels of brain chemicals, or neurotransmitters, like dopamine, gamma aminobutyric acid (GABA), norepinephrine, and serotonin. There are five major classes of legal psychotropic medications: anti-anxiety agents.

Dopamin

 Dopamine is a type of monoamine neurotransmitter. It's made in your brain and acts as a chemical messenger, communicating messages between nerve cells in your brain and your brain and the rest of your body. Dopamine also acts as a hormone. Dopamine is responsible for allowing you to feel pleasure, satisfaction and motivation. When you feel good that you have achieved something, it's because you have a surge of dopamine in the brain. Dopamine is responsible for allowing you to feel pleasure, satisfaction and motivation. When you feel good that you have achieved something, it’s because you have a surge of dopamine in the brain.

It’s possible, however, that you start craving more of this dopamine ‘reward’, which is caused by many pleasant experiences, including eating nice food, having sex, winning a game and earning money. Alcohol and many illegal drugs cause a surge of dopamine too, which is partly why people get addicted to them.

Dopamine also has a role to play in controlling memory, mood, sleep, learning, concentration and body movements.

Activities that make you feel good will also raise dopamine. These include exercising, meditating, having a massage and getting enough sleep. Thinking about your achievements and all the good things in your life can also help.

GABA

Gamma aminobutyric acid (GABA) is a naturally occurring amino acid that works as a neurotransmitter in your brain. Neurotransmitters function as chemical messengers. GABA is considered an inhibitory neurotransmitter because it blocks, or inhibits, certain brain signals and decreases activity in your nervous system.

It is observed that both drug addiction, as well as alcoholism, lead to a person's irresponsible behavior and their increased inclination to take unnecessary risks. Also, while under the influence of drugs and alcohol, people may fall into criminal traps and often commit acts that are socially or legally unacceptable.

The main categories are:
stimulants (e.g. cocaine)
depressants (e.g. alcohol)
opium-related painkillers (e.g. heroin)
hallucinogens (e.g. LSD)

Drugs work in body in a variety of ways. They can interfere with microorganisms (germs) that invade your body, destroy abnormal cells that cause cancer, replace deficient substances (such as hormones or vitamins), or change the way that cells work in your body.

Drug abuse is a serious factor in memory loss and a lack of concentration, which can affect aspects of your life you may not have considered. Drugs can make it hard for you to study, improve your skills at work, learn and retain new concepts, and even pay attention to what's happening around you.

Alcohol, tobacco, or drug use have long been recognized as a cause of memory loss.

Smoking harms memory by reducing the amount of oxygen that gets to the brain. Studies have shown that people who smoke find it more difficult to put faces with names than do nonsmokers. Illegal drugs can change chemicals in the brain that can make it hard to recall memories.


Alcohol and Sleep
Alcohol often is thought of as a sedative or calming drug. While alcohol may induce sleep, the quality of sleep is often fragmented during the second half of the sleep period. Alcohol increases the number of times you awaken in the later half of the night, when the alcohol's relaxing effect wears off. It prevents you from getting the deep sleep and REM sleep you need, because alcohol keeps you in the lighter stages of sleep. With continued consumption just before bedtime, alcohol's sleep-inducing effect may decrease as its disruptive effects continue or increase. The sleep disruption resulting from alcohol use may lead to daytime fatigue and sleepiness. The elderly are at particular risk for alcohol-related sleep disorders, because they achieve higher levels of alcohol in the blood and brain than do younger adults after consuming an equivalent dose. Bedtime alcohol consumption among older adults may lead to unsteadiness if walking is attempted during the night, with increased risk of falls and injuries.

Drugs and Academic achievement
Teens who abuse drugs have lower grades, a higher rate of absence from school and other activities, and an increased potential for dropping out of school. Most people who use drugs regularly don’t consistently do well in school. male student with book over face sitting against wall Studies show that marijuana, for example, affects your attention, memory, and ability to learn. Its effects can last for days or weeks after the drug wears off. So, if you are smoking marijuana daily, you are not functioning at your best. Students who smoke marijuana tend to get lower grades and are more likely to drop out of high school.