Why do humans need sleep?

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After a long, hard day at work, the one thing that most of us look forward to is a long, good night’s sleep. Lack of sleep for even a day leaves us feeling irritable and groggy eyed the next morning.

When sleepy, one even tends to forget hunger, anger and thirst. The sight of a comfortable bed is more inviting than anything else imaginable. Why is this so?

Well, yes. The human body has been wired in such a way that the daily quota of sleep is required for its efficient functioning. Every individual has a circadian rhythm specific to their needs and genes, and thus each person’s sleep cycle varies.

Be it 3 hours or 13 hours, not a single person on this planet can go without at least a few hours of sleep. So why exactly do we need sleep and how does it help? The 10 facts given below elucidate the need for sleep.

  1. To replenish brain glycogen levels.

The brain cells or neurons are driven mainly on glucose making it very essential for glucose and glycogen levels to be high at all times for efficient functioning. When we sleep, we do not require the glucose levels as no conscious brain activity is in progress. The brain thus takes these seven hours to replenish its glycogen levels.

  1. Sleep improves memory.

When we are asleep the brain organizes all information entered that entire day. It refreshes the same information thus enhancing memory. A good 7-8 hours of sleep is required for improving memory.

  1. To prevent expending more energy during colder nights.

During nights when it gets colder, it becomes necessary for the body to expend a lot more energy than usual to keep the body warm. Sleeping during the night helps prevent expending this excess energy.

  1. To repair tissues, muscles and damaged cells.

The body has a self repair mechanism that enables repair of damaged tissues. This happens only when we are sleep. Further, neurons in the brain regenerate during long periods of sleep.

  1. Sleep is necessary for growth.

When asleep, the body releases a chemical that helps in growth. Sleep is thus believed to be necessary for growth.

  1. Acts as a period of rest for body.

Metabolic rate decrease and cardiovascular system gets a break. Though the mind is active even while asleep, the rate of bodily functions slows down when asleep in contrast to when awake.

  1. Sleep is necessary for proper brain development.

Under the conditions of lack of sleep, the areas of the brain critical for making decisions shut down. This is due to the lack of time for growth of brain cells during sleep that help in brain growth and development.

  1. Sleep is linked to proper emotional and physical health.

People who go without sleep for long are believed to have increased irritability and mood swings. Lack of sleep also leads to depression and may cause depression. Thermal regulation in the body is maintained during proper sleep.

  1. The inactivity and energy conservation theory.

The inactivity theory or adaptive theory of sleep suggests that sleeping during night keeps animals safe from harm and predators. The energy conservation theory suggests that sleep helps rejuvenates one’s body and hence helps energize hence giving the feeling of being refreshed.

  1. The restorative and brain plasticity theory.

The restorative theory suggests that sleep restores the physical, cognitive and emotional functions that are lost when awake. As per the brain plasticity theory the changes in brain functions are correlated to sleep.

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