The Power of Sleep


How important is sleep? We learnt from physiology the extremely significant role it plays in safeguarding our health. According to Dr Charles A Czeisler, the Baldino Professor of Sleep Medicine at Harvard Medical School, “If humans average four hours of sleep a night for four to five days, they develop the same level of cognitive impairment as if they’d been awake for 24 hours- equivalent to legal drunkenness. Within ten days, the level of impairment is the same as you’d have gone 48 hours without sleep. This greatly lengthens reaction time, affects judgment, and interferes with problem solving”.

Given how important sleep is, why is it one of the first things we are always willing to sacrifice in our life for whatever pleasure and accomplishment we crave for?

We may think that reducing sleeping time by one or two hours can do no harm. The following table shows the amount of sleep we need based on age:

Age Hours of Sleep Needed
New-borns (0-2 months) 12-18 hours
Infants (3-11 months) 14-15 hours
Toodlers (1-3 years) 12-14 hours
Pre-schoolers (3-5 years) 11-13 hours
School-age children (5-10 years) 10-11 hours
Teens  (10-17 years) 8.5-9.25 hours
Adults 7-9 hours

For centuries, sleep has been thought to be an inactive state. The invention of electroencephalogram in 1929 to enable scientists to record the electrical activity of the brain has changed that perception. Since then, it was proven that sleep is a dynamic process, and our brain is hard at work while we are sleeping.

Sleep is divided into two key phases:non-rapid-eye movement (NREM) and rapid-eye-movement (REM) sleep. Sleep begins with NREM state that is further divided into four stages: onset (Stage 1), light sleep (Stage 2), and deep sleep (Stages 3 and 4).  After about 60-90 minutes of NREM sleep, REM sleep sets in (Stage 5), lasting for approximately 20-30 minutes. Subsequently, NREM sleep returns to start a new sleep cycle. A healthy adult goes through four to six consecutive sleep cycles in one night.

It has long been known that a good night’s sleep reinforces the day’s memories, transferring them from short-term storage into long-term holding. So, burning the midnight oil before the examination is not the best recipe to pass with flying colours.

There are several other repercussions of not getting sufficient sleep. Insufficient sleep slows our metabolism and raises our cortisol level. Cortisol is a stress hormone that increases our cravings for food high in fat and carbohydrates. Increased level of cortisol is linked to insulin resistance, increasing the risk for both diabetics and obesity. Also, when we are deprived of sleep, our body produces more gherlin, the hormone that increases hunger, and less of the hormone leptin, which helps to prevent overeating.

Plus, those who are not getting at least seven hours of sleep every night are losing precious REM sleep, the stage where you burn the most calories. So, those ladies who are obsessed with keeping slim, make sure you have enough sleep first and foremost!

The effect of sleep deprivation has far-ranging effects. Think about the tragic road accidents caused by drivers who fall asleep at the wheels. Insufficient sleep also changes our immune function and may eventually cause a string of diseases. Having sufficient sleep may help fight cancer and keep us healthy.

Dr Mehmet Oz, a cardiothoracic surgeon, television personality and author based in the US, has recommended the following for better sleep:

Dim the light: The blue light from laptops, TV and cell phones suppresses the secretion of melatonin, a sleep-promoting hormone. Read a book instead of watching TV just before bedtime. Place an orange light bulb in the bedside lamp;

Don’t go to bed hungry: A growling empty stomach makes it harder to fall asleep, and that can upset our diet;

Slip on a pair of socks: Wearing socks to bed keeps the blood vessels in our feet dilated, drawing blood away from our core and cooling off and encourages sleep;

More workouts: Exercising four times a week may increase our overall sleep time by 1.25 hours each night.

Considering how important sleep is, sleep should no longer be deemed as an expendable luxury. It is an integral part of our lives and an easy way to keep us healthy and whole!


Written by:
Ms Wee Hui Bieh, AFMSA, December, 2016.

Original Author:
Cheong E Von, medical undergraduate at University College Cork, Ireland

Full article available at magazine, Issue No. 5

This post is also available in: zh-hans简体中文 (Chinese (Simplified))