Sleep is an essential function that allows your body and mind to recharge, leaving you refreshed and alert when you wake up. Healthy sleep also helps the body remain healthy and stave off diseases. Without enough sleep, the brain cannot function properly. This can impair your abilities to concentrate, think clearly, and process memories.
Most adults require between seven and nine hours of nightly sleep. Children and teenagers need substantially more sleep, particularly if they are younger than five years of age. Work schedules, day-to-day stressors, a disruptive bedroom environment, and medical conditions can all prevent us from receiving enough sleep. A healthy diet and positive lifestyle habits can help ensure an adequate amount of sleep each night – but for some, chronic lack of sleep may be the first sign of a sleep disorder.
An internal “body clock” regulates your sleep cycle, controlling when you feel tired and ready for bed or refreshed and alert. This clock operates on a 24-hour cycle known as the circadian rhythm. After waking up from sleep, you’ll become increasingly tired throughout the day. These feelings will peak in the evening leading up to bedtime.
This sleep drive – also known as sleep-wake homeostasis – may be linked to adenosine, an organic compound produced in the brain. Adenosine levels increase throughout the day as you become more tired, and then the body breaks down this compound during sleep.
Light also influences the circadian rhythm. The brain contains a special region of nerve cells known as the hypothalamus, and a cluster of cells in the hypothalamus called the suprachiasmatic nucleus, which processes signals when the eyes are exposed to natural or artificial light. These signals help the brain determine whether it is day or night.
As natural light disappears in the evening, the body will release melatonin, a hormone that induces drowsiness. When the sun rises in the morning, the body will release the hormone known as cortisol that promotes energy and alertness.
Once we fall asleep, our bodies follow a sleep cycle divided into four stages. The first three stages are known as non-rapid eye movement (NREM) sleep, and the final stage is known as rapid eye movement (REM) sleep.
These four stages will repeat cyclically throughout the night until you wake up. For most people, the duration of each cycle will last about 90-120 minutes. NREM sleep constitutes about 75% to 80% of each cycle. You may also wake up briefly during the night but not remember the next day. These episodes are known as “W” stages.
The right amount of sleep largely depends on your age. The National Sleep Foundation recommends the following daily sleep allotment for different age groups.
|Age Group||Age Range||Recommended Amount of Sleep per Day|
|Newborn||0-3 months||14-17 hours|
|Infant||4-11 months||12-15 hours|
|Toddler||1-2 years||11-14 hours|
|Preschool||3-5 years||10-13 hours|
|School-age||6-13 years||9-11 hours|
|Teen||14-17 years||8-10 hours|
|Young Adult||18-25 years||7-9 hours|
|Adult||26-64 years||7-9 hours|
|Older Adult||65 years or older||7-8 hours|
For most adults, at least seven hours of sleep each night is needed for proper cognitive and behavioral functions. An insufficient amount of sleep can lead to serious repercussions. Some studies have shown sleep deprivation leaves people vulnerable to attention lapses, reduced cognition, delayed reactions, and mood shifts.
It’s also been suggested that people can develop a sort of tolerance to chronic sleep deprivation. Even though their brains and bodies struggle due to lack of sleep, they may not be aware of their own deficiencies because less sleep feels normal to them. Additionally, lack of sleep has been linked to a higher risk for certain diseases and medical conditions. These include obesity, type 2 diabetes, high blood pressure, heart disease, stroke, poor mental health, and early death.
Adults who do not receive a sufficient amount of sleep each night can implement some positive lifestyle and sleep habits in order to log the needed seven to nine hours. These include the following:
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