Sleep is a natural part of life that is so important to every aspect of our health. We need sleep to repair, rejuvenate, create hormones effectively, process memories at much more.
It is an essential part of your daily routine as you spend about one-third of your time doing it. However there are many people that aren't getting enough of it at the right times, is as essential to survival as food and water. Without sleep you can’t form or maintain the pathways in your brain that let you learn and create new memories, and it’s harder to concentrate and respond quickly.
Sleep is divided into two categories: REM and non-REM sleep. You begin the night in non-REM sleep followed by a brief period of REM sleep. The cycle continues throughout the night about every 90 minutes.
Deep sleep occurs in the final stage of non-REM sleep.
Stage 1 of non-REM sleep lasts several minutes as you move from being awake to being asleep.
During stage 1:
During stage 2:
During these stages:
The first stage of deep sleep lasts anywhere from 45 to 90 minutes. It lasts for longer periods in the first half of the night and becomes shorter with each sleep cycle.
REM sleep or what some call Stage 5, or your first stage of REM sleep,occurs about 90 minutes after moving through non-REM stages.
During this stage:
What are the benefits of deep sleep?
Glucose metabolism in the brain increases during deep sleep, supporting short-term and long-term memory and overall learning.
Deep sleep is also when the pituitary gland secretes important hormones, like human growth hormone, leading to growth and development of the body.
Other benefits of deep sleep include:
The Anatomy of Sleep
Every person has an internal timekeeping system known informally as the "circadian clock," which is located in the hypothalamus near the front of the brain. The circadian clock is programmed to reset, or "entrain," every 24 hours. This 24-hour cycle, the circadian rhythm, is guided by natural light and plays a major role in hormone production, as well as mood, appetite and digestion, body temperature, and other bodily functions.
The hypothalamus, a peanut-sized structure deep inside the brain, contains groups of nerve cells that act as control centers affecting sleep and arousal. Within the hypothalamus is the suprachiasmatic nucleus (SCN) – clusters of thousands of cells that receive information about light exposure directly from the eyes and control your behavioral rhythm. Some people with damage to the SCN sleep erratically throughout the day because they are not able to match their circadian rhythms with the light-dark cycle.
The brain stem, at the base of the brain, communicates with the hypothalamus to control the transitions between wake and sleep. The brain stem includes structures called the pons, medulla, and midbrain. Sleep-promoting cells within the hypothalamus and the brain stem produce a brain chemical called GABA, which acts to reduce the activity of arousal centers in the hypothalamus and the brain stem. The brain stem ESPECIALLY the pons and medulla also plays a special role in REM sleep sending signals to relax muscles essential for body posture and limb movements, so that we don’t act out our dreams.
This clock consists of roughly 20,000 nuclei clustered together to form a structure called the suprachiasmatic nucleus (SCN). During the day, the retinas in your eyes perceive natural sunlight and transmit signals through a nerve tract that leads directly to the SCN. These signals inform the brain whether it is day or night.
In the evening as natural light begins to disappear, the pineal gland in your brain will produce melatonin, a natural hormone that induces feelings of relaxation and sleepiness.
The thalamus acts as a relay for information from the senses to the cerebral cortex, this is the covering of the brain that interprets and processes information from short- to long-term memory. During most stages of sleep, the thalamus becomes pritty quiet, letting you tune out the external world. But during REM sleep, the thalamus is active, sending the cortex images, sounds, and other sensations that fill our dreams.
The pineal gland which is located within the brain’s two hemispheres, receives signals from the SCN and increases production of the hormone melatonin, which helps put you to sleep once the lights go down. People who have lost their sight and cannot coordinate their natural wake-sleep cycle using natural light can stabilize their sleep patterns by taking small amounts of melatonin at the same time each day.
The basal forebrain, near the front and bottom of the brain, also promotes sleep and wakefulness, while part of the midbrain acts as an arousal system. Release of adenosine (a chemical by-product of cellular energy consumption) from cells in the basal forebrain and probably other regions supports your sleep drive. Caffeine counteracts sleepiness by blocking the actions of adenosine.
The amygdala, an almond-shaped structure involved in processing emotions, becomes increasingly active during REM sleep.
When you wake up in the morning and your eyes perceive natural light, the body will produce another hormone, cortisol, that promotes alertness and wakefulness. The brain stem also communicates with the hypothalamus to produce GABA, a hormone that decreases arousals and helps the body wind down.
In addition to circadian rhythm, your sleep is also regulated by a process called sleep-wake homeostasis. Also known as your sleep drive, this mechanism regulates feelings of tiredness and wakefulness. For every hour you're awake, your sleep drive will become stronger, and these feelings will culminate right before you go to bed.
Your circadian rhythm and sleep-wake homeostasis do not exist in a vacuum. Circadian rhythm disorders can cause you to feel tired and alert at times of the day that do not align with natural light cycles. Examples range from mild conditions such as jet lag to more serious conditions such as advanced or delayed sleep-wake phase disorder, irregular sleep-wake rhythm disorder, and shift work disorder. Factors that can affect or alter your sleep-wake homeostasis include light exposure, diet, stress, medical conditions, and your sleep environment.
When sleep goes wrong
In a 2014 Ted Talk program, neuroscience researcher Jeff Illiff presented mind-blowing research on how the brain deals with its “waste.” He explained that researchers were astonished to find that when we sleep, channels open up around the blood vessels in the brain. These channels flush the brain with cerebrospinal fluid (CSF), which effectively cleans the brain, taking away the waste products from normal metabolism.
When you’re not getting enough sleep, or if your quality of sleep is poor, all of the positive things that happen in sleep—as described above—decrease. Your body is unable to repair effectively, biological processes are disturbed, and there are significant effects on brain function and cognition.
Lack of quality sleep can impact:
What Happens to Your Body When You Don't Sleep?
Sleep deprivation often leads to tiredness during the day. You may wake up feeling less refreshed and alert than you might after seven to nine hours of uninterrupted sleep, and this can affect how you perform in different professional and social settings. Other immediate side effects of inadequate sleep include anger and irritability, impulsivity and poor decision-making, and trouble concentrating.
HOWEVER chronic lack of sleep can lead too...
It can be very detrimental to your long-term health.
Complications that may arise include:
Sleep hygiene is a collection of practices or behaviours around sleep that help to promote melatonin production. Improving our sleep hygiene helps prepare our body for good quality, restorative sleep.
What if I am a Shift Worker?
People who work overnight shifts, early morning shifts, or rotating shifts (both day shifts and night shifts) may develop something called shift work disorder (SWD). Studies show that those with SWD have poorer sleep quality than day workers. They may take longer to fall asleep, experience insomnia, and feel excessive sleepiness while awake. This is caused by attempts to sleep in daylight, which opposes natural circadian rhythms. Poor sleep hygiene further aggravates the problem. SWD is associated with decreased alertness, higher risk of work-related accidents, and increased depression and anxiety. SWD is also associated with metabolic changes increasing the risk of heart disease, obesity, and digestive problems caused by irregular eating habits or poor diet. The following tips can help if you work nontraditional hours:
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