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What is Sleep?

Sleep is a state of mind that occurs naturally.

While you are sleeping, your sensory activity is relatively inhibited as well nearly all your voluntary muscles. Sleep is characterized by altered stages of consciousness. Your body will go through two different modes; REM sleep and non-REM sleep. REM stands for Rapid Eye Movement. This is characterized by the rapid movements of the eyes. It is also accompanied with low muscle tone throughout the body. The REM sleep cycle is also known as a paradoxical sleep and sometimes a desynchronized sleep because of the physiological similarities to the waking stage. This includes the rapid, low voltage desynchronized brain waves.


During the REM sleep cycle, your body experiences dreaming. A dream is an experience that typically happens in narrative form. It will resemble your waking life during the dream, but afterwards you are able to recognize it as fantasy. Dreams can be successions of images, ideas, emotions, or sensations. During the REM sleep cycle, your brain activity is extremely high and can resemble being awake. Your eyes are continuously moving during this stage of sleep. The length of dreams can vary however. Some may only last for a few seconds, while others can last twenty to thirty minutes. If you are awakened during the REM cycle, you will be more likely to remember your dream. The average person is said to have anywhere from three to five dreams a night. Sometimes a person can reach up to seven dreams in one night. Imagine if you could remember all of them! You would have some good stories to tell in the morning. For a person getting the average eight hours of sleep a night, they will typically dream during the two hour window of REM sleep.

Non-REM sleep is when there is little or no eye movement. Dreaming is extremely rare during the non-REM cycle and your muscles are not paralyzed. Sleepwalking may occur during the non-REM cycle. According to researchers, the mental activity that takes place during the non-REM is believed to be thought-like, whereas the mental activity during REM sleep is more hallucinatory and bizarre.

Non-REM sleep will occur before REM sleep does. After the non-REM stage comes a transitional period called slow wave sleep or deep sleep. It is during this cycle that the body temperature and heart rate fall. Your brain will use less energy. REM sleep is a smaller portion of time. The reason that dreaming will occur at this phase is because the desynchronized and fast brain waves, the eye movements, the loss of muscle tone, and the suspension of homeostasis.


The sleep cycle of non-REM and REM will normally last about ninety minutes. It also occurs four to six times in a good night’s rest. Awakening can mean the end of your sleep cycles. It sometimes can happen in the middle of the night, and you might take a moment to take in your surroundings, perhaps adjust a pillow or blanket, and then fall back asleep. The awakening typically happens soon after the REM cycle, or sometimes in the middle of the REM cycle. When you awake, the electrical activation in your brain is heightened. It begins with the thalamus and spreads throughout the cortex.

While you sleep, most of your body’s systems are in an anabolic state. They are working to help restore the immune, nervous, skeletal, and muscular systems. Restoring these systems help to maintain mood, memory, and cognitive performance. It also plays a role in the functions of the endocrine and immune systems. Everyone has an internal clock, otherwise known as a circadian clock, that will promote sleep at night. Your sleep timing is directly related to the hormonal signals the circadian clock is giving off. It uses these signals to create an internal day and night rhythm. The circadian clock counteracts the need to sleep during the day and promotes sleep at night. When our circadian clock is working to a regular rhythm, the individual is said to be “entrained”. This means that the rhythm the circadian clock has created is persistent, that even if the outside signals cease to happen, the person would still continue to experience the rhythmic increases and decreases of the body temperature and release of melatonin during a 24 hour period. Scientists refer to this as, “free running of the circadian rhythm.”


That being said, the internal circadian clock is influenced by changes in light. The light is how your body determines what time it is. If you were to expose yourself to small amounts of light during the night, your body could increase in temperature, suppress melatonin, and increase its cognitive ability. Blue light can especially interfere with the circadian clock. This is why it is strongly suggested that the bedroom should be free from electronics such as TV, smart phones, laptops, and tablets. Sometimes people can become desynchronized from their internal circadian clock. This can be from working night shifts or traveling long distances. Even if a person is sleep deprived and feels tired, they may have problems staying asleep at the peak of their circadian cycle. When a person is “entrained” to the sun, they will fall asleep a few hours after sunset, their body will then experience the temperature drop, and then they will wake up a few hours after sunrise.

While we sleep, we are experiencing the most physiological changes in our brain. During the non-REM cycle, the brain will use significantly less energy than when you are awake. When brain activity is reduced, it is able to restore the supply of adenosine triphosphate, which is the molecule for short term storage and energy transportation. While you are sleeping, your sensory threshold is increased. We react to fewer stimuli. However, we can still respond to loud noises and other sensory events.


The amount of sleep people need will vary by age. Researchers have shown that 6-7 hours of sleep a night will result in longevity and cardiac health. It’s important to make sure that you are getting enough sleep. The body is restoring itself while you sleep. It’s also healing and removing waste that builds up during times of activity. The brain is also in need of sleep so that it can restore itself as well. The sleeping brain can remove metabolic waste faster than when the body is awake. Sleep is crucial for our bodies and overall health; mentally and physically. Our bodies cannot function without it. We need our bodies to be working at 100%, so we need to make sure that we are giving our body time to rest and heal from all the hard work it does.