Sleep or sleeping has been defined in many ways, which all mean the same. This is how it is defined.

Sleep is a

  • Natural periodic (usually nocturnal) state of rest of body and mind in which the eyes are closed and wakefulness is not present
  • Temporary suspension of consciousness and volition (the act of making a conscious choice or decision)
  • Behavioral state in which voluntary body functions are partially suspended
  • Characteristic immobile body posture
  • Diminished sensitivity to external stimuli, which is reversible.

According to the National Sleep Foundation, adults require seven to nine hours of sleep every day. Athletes, however, may be able to perform better if they sleep for 10 hours.

The benefits of getting enough sleep are tremendous and extend from the macro level to the micro level.

Today’s fast-paced and tension-filled lifestyle has led to a vast increase in people who suffer from sleep deprivation.

According to recent data, almost 30% of Americans are sleeping 6 hours or less. In the rest of the world, other countries are also reporting a decline in the sleep duration of their population.

The clinical complications of sleep deprivation on the body are serious and this condition should not be ignored.

There are many disorders that deprive you of sleep. The most common is insomnia. Others include sleep apnea, narcolepsy, sleeping sickness, sleepwalking, and night terrors.

Why is sleep important?  

As mentioned above, sleep is essential for all animals and is a complex process by which not only the mind but the body too is restored, renewed, and rejuvenated.

Its importance can be gauged from the fact that many diseases are caused as a result of sleep disorders. Lack of sleep not only causes mental insufficiency but also physical inadequacy.

Deprivation causes reduced energy levels, lack of concentration, a depressed mood, and reduced overall efficiency. Long periods of sleep deprivation have resulted in stress-related deaths in lab animals, which could even happen to humans.


Getting the required amount of sleep has many benefits:

  • Sleep slows down metabolism thereby saving and restoring energy.
  • During a good slumber, most neurons of the brain decrease their activity thereby helping to replenish stores of neurotransmitters (chemical inter-neuron messengers in the brain), which are responsible for mood sentiment.
  • When you are asleep, the brain gets to rest, which helps it to restore itself.
  • The neurons that are involved with learning and memory, rest, and, therefore, we are mentally sharper and more attentive during the next day with a good night’s sleep compared to otherwise. Working memory (ability to actively store information in the mind), which is important for high-level cognitive functions has been shown to be affected by lack of proper sleep.
  • Sleep helps to keep your immune system healthy. Its deprivation adversely affects the immune system causing delayed healing of wounds.
  • Sleep is necessary for our nervous system to work properly.
  • Deep slumber is associated with the release of growth hormones in children and young adults. Body cells show increased activity and reduced breakdown of proteins, which helps in cell growth and repair of damage caused by stress and other external factors.

What happens during sleep | Physiology

Many biological processes take place when we are asleep:

  • The brain stores new information and gets rid of toxic waste.
  • Nerve cells reorganize and build communication channels. This helps the brain to function better. 
  • Cell repair takes place, which helps to restore energy and releases molecules like hormones and proteins.
  • Sleeping is seen in all mammals, all birds, most reptiles, fish, and amphibians, and forms an essential part of living. William Shakespeare described it best when he called sleep “nature’s soft nurse”.
  • Considering the fact that on average, we spend 25 years of our life sleeping (that is 1/3rd of our life), it is still a subject of intense research and scientists are still trying to figure out its complete benefits and mechanism.
  • Although EEG (electroencephalogram) records the brainwaves, scientists still cannot say what the brain exactly does during sleep besides producing dreams.
  • Though sleep is the absence of wakefulness, many areas in the brain are active during the time you are not awake. It is the brain, which is responsible for generating sleep.
  • When you are asleep, the body and mind are both awake and active, performing their various functions such as correcting chemical imbalances, maintaining sugar levels, sharpening memory, and lots more.

Sleep Debt | Sleep Deficit

Sleep debt or deficit is the cumulative effect on the body that accumulates due to not getting enough sleep. It is the difference between the amount of sleep you need and the amount you actually get.

For example, if your body needs eight hours of sleep every night but you sleep only for six hours, you have accumulated two hours of sleep debt. Every time you lose out on sleep hours, your deficit goes on accumulating and mounting.

Long-term sleep deprivation can cause and worsen many existing major health conditions. A large sleep deficit can cause physical, emotional, and mental fatigue.

High-level cognitive functions also diminish. In addition, the health complications increase, putting you at a growing risk for diabetes, heart disease, stroke, and cognitive loss.

Regular sleep deprivation is also linked to reduced immune function, unregulated metabolism, an increase in weight, and a greater risk of falls and accidents. 

However, how much sleep debt can be accumulated by a human is still to be established. You must try and get the required hours of sleep every night.