What Part Of The Brain Controls Sleep? What Are The Stages Of Sleep?

Our brain is the most complex yet the most superior part of our body. It has control over everything, from our emotions to our sleep, each and everything is under its control. Follow this article to learn about what part of the brain controls sleep and what are the stages of sleep.

Human brain is a very unique and complex organ, with thousands of nerves and brain cells, there are also different parts of the human brain designated for different jobs. Like the thalamus controls emotions and personality. In the same way, the hypothalamus is the part of the brain that vends with the sleeping patterns of a person. The hypothalamus deals with the stages of sleep.

While dealing with sleep, it is not just hypothalamus that is responsible for it, there are also many sub-parts that are equally responsible. The brain stem, forebrain, amygdala, and the thalamus as well. These parts of the brain also deal with the different stages of sleep a person goes through and the mechanism through which sleep works.

Follow this article to explore more about what part of the brain controls sleep and what are the stages of sleep.

What part of the brain controls sleep?

Just like everything else in our body, sleep is also controlled by our brain and its parts. The brain cells and the brain chemicals make sure that a person gets to have a good night’s sleep. Apart from the hypothalamus, following are the parts of the brain that controls sleep.

  • Hypothalamus
  • Thalamus
  • Brain stem
  • Pineal gland
  • Basal forebrain
  • Amygdala


The hypothalamus has neurons called ventrolateral preoptic nucleus that have neurons linked with the arousal centers. It generates hormones that are linked with the arousal like when having sex. But when the brain is ready to go to sleep then, the hypothalamus stops promoting the arousal chemicals and this shut down causes the brain to lose its productivity and go to sleep.


The thalamus is a part of the brain that transfers information from the hypothalamus and cortex, the thalamus is usually an active part of the brain but when a person is in their sleep then, the thalamus will be inactive and it will let the person sleep. But if a person is experiencing REM sleep like their eyes are rapidly moving then, the thalamus will become active and capture all the necessary information there is about their surroundings.

Brain stem:

The brain stem communicates with the hypothalamus and gives away a chemical called GABA. It reduces any activity there is happening in the brain and relaxes the muscles in the body. Its function is to relax every muscle in the body so there is movement when a person is sleeping.

Pineal gland:

Pineal gland is located in between the two hemispheres. Its main function is to release a brain chemical called melatonin. Melatonin helps a person fall asleep almost instantly as soon as the light goes out. Pineal gland also helps a person maintain their sleep cycle and it also matches a person’s bodily rhythm with their current stage of sleep.

Basal forebrain:

Basal forebrain is located at the bottom of our brain and it is an essential part of our midbrain. It helps a person fall asleep and stay awake. Basal forebrain also helps a person to immediately wake up when there is a threat in their surroundings. The basal forebrain also releases the arousal chemicals in our brain.


Amygdala is basically responsible for emotions but it also plays an important role when a person is in their REM sleep. It delivers the correct emotional response into the brain’s of a person when they see something in their dream which has an emotional connection with them. Amygdala is usually a very disconnected part of the brain and it works on its own.

What are the different stages of sleep?

A person cannot just fall asleep immediately, there is a complete cycle that our brain follows. According to scientists, a human’s sleep is divided into four main stages and every stage is different from the other. Following are the different stages of sleep.

  • Stage 1 – drowsy
  • Stage 2 – light sleep
  • Stage 3 – deep sleep
  • Stage 4 – REM sleep

Stage 1 – drowsy:

Stage one sleep is the state of drowsiness. A person’s body is relaxed and they are about to fall asleep but still the brain is aware of its surroundings. This is the first stage of sleep and it usually lasts for ten to fifteen minutes. Your brain is half asleep and half awake, its productivity level is extremely low and this will make you drowsy.

Stage 2 – light sleep:

Stage two is when a person enters light sleep. The body is relaxed and every muscle in the body is at rest, the brain is no longer productive, and melatonin is taking over your brain. But you are not too deep in your sleep. This means that you can easily wake up if someone even nudges you a little. There is a possibility that a person can be in their stage two of sleep for a long time, it is not easy going into deep sleep almost immediately.

Stage 3 – deep sleep:

At this stage of sleep, your brain is not productive and the waves in your brain are slower. When a person is in their deep sleep then, their heartbeat will be slow and their breathing will also become slower than usual. At this stage, it might be tough to wake up a person because they are in their deep sleep. But being in a deep sleep does not mean that a person has entered their REM sleep. It takes at least thirty minutes before a person goes into stage four.

Stage 4 – REM sleep:

REM sleep occurs when a person enters their deep sleep for more than thirty minutes. Usually when a person is in their REM sleep their arms and legs are paralyzed so a person does not move them during their dreams. But the eye movement will be rapid and the brain activity will also increase. This is mostly because there is a possibility that a person might wake up from their sleep if they see something unpleasant in their dream.

What happens to your body when you are asleep?

Your body and your brain are not completely useless when you are asleep. If you ever wonder what happens inside your body when you are in your deep sleep then, following are the things that happen to your body when you are asleep.

  • Breathing
  • Heart
  • Brain
  • Muscles
  • Memory
  • Brain stem
  • Hormones


When a person falls asleep, their breathing is low and it stays like this during their sleep. But once a person enters their REM sleep then, there is a possibility that their breathing will become fast. This is because in REM sleep a person is in the state to wake up because of their dreams. If you notice, when a person wakes up in the middle of the night after a bad dream then their breathing will be fast. This is because they were in their REM sleep.


When a person is in their deep sleep then, their blood pressure and their pulse will be slow. This gives a chance for the heart and the blood vessels to rest for a while. The blood circulation is normal and there is not much pressure on the heart. But this only happens at stage three of the sleep cycle. During REM sleep the blood pressure is high and the heartbeat is fast.


During your deep sleep, your brain’s activity is less and the waves in your brain are slow. The productivity level of your brain is low and this gives a chance to your brain for resting a bit. But when you enter your REM sleep then, your brain is active and it takes notice of each and everything, it immediately alerts all the senses.


During your deep sleep, all of your muscles are relaxed so this gives your muscles a chance to repair themselves. Your blood circulation is normal and your entire system is at rest. This will help your body release chemicals that can strengthen your body and make your muscles stronger. This is one of the reasons why getting a good night’s sleep is extremely important.


When you are in deep sleep then, your brain will delete all the useless information that has been stored in your memory and make space for new things. According to scientists, when a person gets tired of solving a puzzle then they should try to sleep and relax. This way when they wake up, they will be able to solve the exact same puzzle more efficiently. This happens because when you wake up after a good sleep then, your brain will be more productive.

Brain stem:

Your brain stem is the one of the most vital parts of your brain. It attaches the hypothalamus with the rest of the brain. When a person is in their deep sleep then, the brain stem relaxes but when you enter your REM sleep then, the brain stem immediately sends signals to the rest of the body to make the arms and the legs paralyzed so you do not hurt yourself during sleep.


During your deep sleep, your body functions to make your hormones balanced. When a person is asleep then, their stress hormones will come down and even your cholesterol levels will also come down. According to scientists, when a person suffers from insomnia, it is mostly because their hormones are imbalanced.

What are the sleep mechanisms?

A person’s sleep mechanism makes sure that you wake up and sleep without any difficulty. Following are the two biological sleep mechanisms in a person.

  • Circadian rhythm
  • Homeostasis

Circadian rhythm:

Circadian rhythm is like a biological clock. It keeps track of your routine like when you wake up and when you fall asleep. Once you have fallen into a routine then, naturally your body will start to shut down at night and you will feel drowsy and you will wake up naturally on your own time without an alarm. The circadian rhythm follows the instructions of the environment like light and temperature.

Sleep/Wake Homeostasis:

Homeostasis deals with the sleeping and waking up of a person. It takes care of your sleep drive and when you pass your daily time of going to bed then, this sleep drive will only become stronger with each passing minute. Homeostasis is also inspired by the environment, medical conditions, stress, and medications.

How can you get a good night’s sleep?

It is important that we get quality sleep for our brain to work properly. If we are not able to sleep properly because of anything then, our brain will become foggy and we will have trouble focusing and completing our daily tasks. Following are the things you can do to get a good night’s sleep.

  • Set a routine
  • Comfortable environment
  • No distraction
  • Avoid eating before going to bed

Set a routine:

It is supreme for you to set a routine. When your body is used to sleeping at a certain time then, your circadian rhythm will naturally increase your sleep drive in a timely manner. This also goes for waking up, you will naturally wake up without anything. You can also add reading a book before going to bed or doing your skincare, this way your body will automatically make you do these things before going to bed.

Comfortable environment:

You must have a comfortable environment for yourself. Your bedding, your room temperature, and your clothes all of these things should be comfortable and breathable. Make sure you wear light clothing while sleeping and your pillows are soft and comfortable. Your room temperature should be ideal, neither too cold nor too hot.

No distraction:

Make sure that all of your devices are off and there is no source of light in your room. Keep your mobile phones, tablets, and laptops aside and try to relax your muscles. Do not think about anything else and try to visualize a happy place. Relax your muscles, this will help you fall asleep peacefully.

Avoid eating before going to bed:

It is not wise to eat before going to bed. You should not consume any food and caffeinated drinks at least two hours before going to bed. This will help your digestion system to relax and your sugar levels will not be high, making it easy for you to fall asleep.


Sleep, like all other bodily functions, is controlled by the brain. This intricate organ produces chemicals such as melatonin that facilitate sleep. The hypothalamus is the part of the brain responsible for regulating sleep and wakefulness. It sends signals to the thalamus, forebrain, brain stem, and amygdala, which then reduce brain activity and slow down brain waves, helping a person achieve a restful sleep.

Falling asleep is a gradual process that occurs in four stages within a sleep cycle. The first stage induces drowsiness and increases the sleep drive, which continues to build as long as a person remains awake. The second stage is light sleep, followed by the third stage of deep sleep, and finally, the REM (Rapid Eye Movement) sleep stage. While brain activity is minimal during the first three stages, REM sleep involves active brain function and partial paralysis of the arms and legs to prevent injury.

Adequate sleep is crucial for proper brain function. Scientists suggest that if someone is struggling with a problem, it is beneficial to take a break and sleep. Sufficient REM sleep can clear the mind, allowing for more efficient problem-solving upon waking.