sleep

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Sleep is an important part of your daily routine – you spend about a third of your time doing it. Adequate sleep—and enough of it at the right time—is as essential to survival as food and water. Without sleep, you cannot create and maintain new neural pathways in the brain that help you learn and create new memories, and it becomes harder to focus and respond quickly without enough sleep.

Sleep is important for a number of brain functions, including how nerve cells (neurons) communicate with each other. In fact, your brain and body are extremely active when you sleep. Recent findings show that sleep plays an important role in eliminating toxins from your brain.

Everyone needs sleep. Sleep affects almost every tissue and system in the body—from the brain, heart, and lungs to metabolism, immune function, mood, and resistance to disease. Research shows that chronic lack of sleep or lack of sleep increases disorders such as high blood pressure, cardiovascular diseases, diabetes, depression and obesity. With the new methods that scientists have now discovered, it is clear that sleep is a complex and dynamic process that affects how you function.

Anatomy of sleep

Several structures within the brain are associated with sleep.

First, the hypothalamus, a peanut-sized structure deep in the brain, which contains a group of nerve cells that act as control centers affecting sleep and agitation. Inside the hypothalamus there is a section (SCN) that receives information about light directly from the eyes and controls its behavioral rhythm. Some people with SCN disorders experience sudden daytime sleepiness because they are unable to match their circadian rhythm with the light-dark cycle. Most blind people have this type of sensitivity and can change their sleep/wake cycle.

The brainstem communicates with the hypothalamus to control the transition between wakefulness and sleep. (Our brain includes structures known as pons, medulla, and midbrain.) The cells responsible for sleep in the hypothalamus and brain stem produce a magnetic chemical called GABA, which reduces the activity of excitable centers in the hypothalamus and brain stem. It becomes the brain. The brainstem (especially the pons and medulla) also plays an important role in REM sleep. Through it, the brain sends signals to reduce body movements during sleep.

The thalamus acts as a relay for information from the senses to the cerebral cortex (the covering of the brain that interprets and processes information from short-term and long-term memory). During most stages of sleep, the thalamus relaxes, allowing you to tune in to the outside world. But during REM sleep, the thalamus is active and is responsible for sending the brain images, sounds, and other sensations that fill our dreams.

The pineal gland, located in both hemispheres of the brain, receives signals from the SCN and increases the production of the hormone melatonin, and after the ambient light has dimmed, you can sleep. People who have lost an eye and cannot coordinate their natural sleep and sleep cycles using natural light can stabilize their sleep patterns by taking small amounts of melatonin at the same time. Scientists believe that the ups and downs of melatonin secretion over time are related to the adaptation of the body’s circadian rhythm to the external cycle of light and darkness.

The basal forebrain, near the front and bottom of the brain, causes sleep and wakefulness, while part of the midbrain acts as an excitatory system. The release of adenosine (a chemical produced from cellular energy consumption) from the basal cells of the forebrain and possibly other regions supports your sleep onset. Caffeine controls sleepiness by blocking the actions of adenosine. The amygdala, an almond-shaped structure involved in emotion processing, becomes increasingly active during REM sleep.

stages of sleep

There are two basic types of sleep: Rapid eye sleep (REM) and non-REM sleep, which has three different stages. Each is associated with specific brain waves and neural activity. In a typical night, you nap several times in all stages of non-REM and REM sleep, with the deepest REM periods experienced near the morning.

The first stage of non-REM sleep is the transition from wakefulness to sleep. During this short period (a few minutes) of relatively little sleep, your heart rate, breathing, and eye movements decrease, and muscles contract with occasional jerks. Your brainwaves tend to shift from fast, high-frequency daily patterns to slow waves.

The second stage of non-REM sleep is a period of light sleep experienced before deeper sleep. Your heart rate and breathing slow and your muscles relax even more than before. Your body temperature drops and eye movements stop. Brain wave activity slows down, but brain activity is accompanied by small spikes of electrical activity. Your sleep cycles are more frequent in this stage than in other stages.

Stage 3 non-REM sleep is the period of deep sleep that leaves you feeling refreshed in the morning. It occurs in long periods in the first half of the night. Heart rate and breathing reach their lowest levels during sleep. Your muscles are relaxed and you hardly wake up. Brain waves slow down during this period.

REM sleep first occurs about 90 minutes after falling asleep. Your eyes are moving fast. The frequency activity of the brain becomes closer to that which exists in wakefulness. Your breathing becomes faster and more irregular, and your heart rate and blood pressure increase to near-awake levels. Most of your dreams occur during REM sleep, although some can also occur during non-REM sleep. Your arm and leg muscles are temporarily paralyzed, preventing them from moving during sleep. As you get older, you spend less time in REM sleep. Memory consolidation most likely requires non-REM and REM sleep at the same time.

Mechanism of sleep

The two factors of circadian rhythm and homeostasis interact to regulate when you wake up and when you go to sleep.

Pregnancy rhythms guide a wide range of functions from daily fluctuations in wakefulness to body temperature, metabolism, and hormone release. They control your sleep time and make you sleepy at night and wake you up in the morning without an alarm. Your body’s biological clock, which is based on a roughly 24-hour day, controls most daily rhythms. Digital rhythms are synchronized with environmental cues (light, temperature) to the actual time of day, but persist even in the absence of cues.

Sleep homeostasis follows your need for sleep.

Factors that affect your need for sleep include medical conditions, medications, stress, sleep environment, and what you eat and drink. Exposure to light may have the greatest effect. Specialized cells in your retina process light and tell the brain whether it’s day or night and can start or delay our sleep-wake cycle. Exposure to light wakes us up.

Night shift workers fall asleep during the day and fall asleep with difficulty because the natural circadian rhythm is disrupted.

Let’s get to know the brain better

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Let’s get to know the brain better

Every animal such as mammals, birds, reptiles, fish, amphibians – like humans has an organ called the brain. But the human brain is unique. Although our brain is not the largest among living things, it gives us the power to speak, imagine and solve problems. This is truly an amazing organ.


The brain performs an incredible number of tasks, including:

It controls body temperature, blood pressure, heart rate and breathing.

Your brain receives information from your various senses (sight, hearing, smell, taste, and touch) about the world around you.

It controls when you move, talk, stand or sit, and shake objects.

It allows you to have your own feelings, dreams, and thoughts.

All these tasks are regulated and coordinated by a member that is the size of a small cauliflower.


The brain, spinal cord and peripheral nerves are a complex and integrated information processing and control system known as the central nervous system. Together, they regulate all conscious and unconscious aspects of your life. The scientific study of the brain and nervous system is called neuroscience or neurobiology.

Your brain is made up of approximately 100 billion nerve cells called neurons. Neurons have an amazing ability to collect and transmit electrochemical signals

Neurons are similar to other cells, but their electrochemical aspect enables them to send signals over long distances.

Neurons have three basic parts:

cell body This main part contains all the necessary components of the cell, such as the nucleus (containing DNA), endoplasmic reticulum and ribosomes (to make proteins) and mitochondria (to make energy).

The axon, which carries the electrochemical message (nerve impulse or action potential) along the length of the cell, like a cable. Depending on the type of neuron, axons can be covered with a thin layer of myelin sheath, like the insulation of an electric wire. Myelin is made of fat and protein and helps speed the transmission of a nerve impulse down a long axon. Myelinated neurons are typically found in peripheral nerves (sensory and motor neurons), while unmyelinated neurons are found in the brain and spinal cord.

Dendrites or nerve endings. These tiny projections make connections to other cells and allow the neuron to communicate with other cells or sense the environment. Dendrites can be seen at one or both ends of a cell.

Neurons have different sizes. For example, a sensory neuron from the tip of your finger has an axon that travels the length of the arm to reach the brain, whereas a neuron in the brain may be only a few millimeters long.


They are different depending on the function of the neurons. Motor neurons that control muscle contraction are located on one side of the cell body, at the other end of the dendrites, which are connected to the cell body through a long axon.

Sensory neurons have dendrites at both ends, and are connected by a long axon to the cell body in the middle. Interneurons or interneurons carry information between motor and sensory neurons.

These basic parts of the nervous system are also different according to their function.

Sensory neurons transmit signals from the external parts of the body (environment) to the central nervous system.

Motor neurons, or motoneurons, carry signals from the central nervous system to the outside parts of your body (muscles, skin, glands).

Interneurons connect different neurons in the brain and spinal cord.

The simplest type of neural pathway is a single-synaptic (single-connection) reflex pathway, such as the knee-jerk reflex. When the doctor taps the right spot on your knee with a rubber mallet, the receptors send a signal to the spinal cord through a sensory neuron. The sensory neuron transmits this message to a motor neuron that controls your leg muscles. Nerve impulses are sent down the motor neuron and lead to muscle contraction. This response is an intense muscle movement that happens quickly and is not processed in the brain. Humans have many such reflexes, but the more complex they become, the more complex they become, and the brain is involved in many of them.

The brain has the following parts:


The brainstem, which includes the medulla (a large part of the upper spinal cord), the pons, and the midbrain. The brain controls reflexes and automatic functions (heart rate, blood pressure), limb movements, and visceral functions (digestion, urination).

The cerebellum receives information from the vestibular system that indicates position and movement and uses this data to coordinate limb movements.

The hypothalamus and pituitary gland are responsible for intellectual functions, body temperature, and behavioral responses such as feeding, drinking, sexual response, violence, and pleasure.

The brain (also called the cerebral cortex or cortex) includes the cortex, many fiber tracts (corpus callosum) and some deeper structures (basal ganglia, amygdala, and hippocampus). These parts integrate information from all sensory organs, initiate movement, control emotions, and memory and thinking processes.

The lower brain includes the spinal cord, brain stem and diencephalon. The midbrain itself includes the medulla, corpus callosum, midbrain, hypothalamus, and thalamus.

Within each of these structures are nerve cell centers, known as nuclei, that are specialized for specific functions (breathing, heart regulation, sleep).

Medulla – The medulla contains a center for regulating blood pressure and breathing, as well as a section for distributing information from the sensory organs that come from the cranial nerves.

corpus callosum – this part contains the center that transmits movement and position information from the cerebellum to the cortex. It also contains nuclei involved in breathing, taste and sleep and connects the medulla to the midbrain.

The midbrain includes centers that connect different parts of the brain involved in motor function (cerebellum, basal ganglia, cerebral cortex), eye movements, and auditory control. One part, called the substantia nigra, is involved in voluntary movements. When this part does not work, tremors like Parkinson’s disease symptoms are experienced.

Thalamus – The thalamus connects the sensory pathways entering the brain to the appropriate cortical areas, makes aware of sensory information and participates in the exchange of motor information between the cerebellum, basal ganglia and cerebral cortex.

Hypothalamus – The hypothalamus contains the center that controls hormonal secretions from the pituitary gland. These centers monitor sexual reproduction, eating, drinking, growth and behavior of mothers such as lactation (milk production in mammals). The hypothalamus is also involved in almost every aspect of behavior, including your biological “clock” which is associated with the light-dark cycle (daily rhythms).

How is the brain activity when studying?

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While studying, different parts of the brain are activated at the same time. For example, parts of the back of the brain will be more active to shape the information that the eyes receive from the book while reading. To understand the complexities of the text, other parts of the brain that are located in the front part of the brain will come into action.

The mechanism of discovering changes in brain activity during different activities is possible using different tools, including fMRI. This technology helps scientists to examine brain activity while performing a task such as studying. In some forms of this test, attention is paid to changes in blood supply to the brain or oxygen consumption.

Most of the studies that have been done on reading a book and examining brain activity during it have led to an almost universal pattern in brain activity. First, islands in the frontal, temporal and occipital parts are activated and gradually they connect in parts.

Depending on the subject being studied, parts of these active areas may be more or less active. For example, when reading colorful texts or with many pictures, most of the activities are seen in the back of the brain, and when reading mathematical texts or with abstract concepts, the activities of the front of the brain may increase. When reading texts that require a language challenge, such as foreign or non-native texts, parts of the head and above the ears become more active.

In the pictures below, you can see examples of brain activity in different situations.