Anyone who has woken up without a proper night’s sleep can attest to the noticeable differences in the way one thinks, feels and functions.

However, sleep’s true significance on our overall health and functioning is even greater than one would think. Here’s what the evidence says.


Sleep and Our Body

Before the invention of the light bulb, people slept an average of 10 hours a night. Today, many get a mere 5 hours of sleep. The relative novelty of this change in routine has several implications. The biggest one: it’s probably not how our body was designed to function.

Although scientists are still studying these concepts, increasing evidence shows that sleep can make all the difference to our overall health. Inadequate sleep could severely impact our metabolism, which in turn leads to a higher risk of obesity and consequent lifestyle diseases like diabetes.1

In fact – and here’s something that sleep-lovers will truly appreciate – sleeping has been shown to be one of the most important activities of the 24-hour day, when it comes to the modulation of our body’s functions. This also explains why we burn so many calories when we sleep.1 Even the advice to “sleep over it” gets a scientific nod. Our moods and cognition are clarified and organised when we sleep. This is also a particularly importantly aspect of our personal safety; driving after a night of insufficient sleep is tantamount to driving after an alcoholic drink.

So, why does sleep affect us in such fundamental ways? The answer lies in the processes that take place during our sleep cycle.

A sleep cycle that has two main states:

(i) Rapid Eye Movement (REM) sleep: a state of consciousness during which our muscles relax, but our brain is still active – this is where dreams occur.

(ii) Non-rapid Eye Movement (NREM) sleep: here’s when our body repairs itself, regrows tissues, builds bone and muscle, regulates hormones, and strengthens the immune system.

These two states typically alternate through the night for 60–90 minutes each; in effect, 7-8 hours of sleep would include four to five sleep cycles.

Sleeping less than 6 hours a night, or poor sleep quality in general, leads to ‘sleep dept’ – where one carries around a heavy load of sleepiness day after day, with or without sleep orders like insomnia and sleep apnea.


Sleep Debt and Our Hormones

Our sleep regulates at least ten different hormones that we are aware of. In fact, the 24-hour sleep/wake cycle, known as the ‘circadian cycle’, controls 10-15% of our genes.4

It’s unsurprising, then, that sleep disorders have been linked to hormonal problems (including impotence). Amongst these, Polycystic Ovary Syndrome (PCOS) is a particularly common hormonal condition that occurs in women, and goes on to cause skin problems and weight gain.2 Sleep disorders can even cause depression, by disrupting a mood-regulating hormone called ‘serotonin’.

Sleep debt, in itself, has been associated with a number of health problems. It can cause obesity, by potentially altering the key appetite hormones (e.g. leptin and ghrelin) in a manner that enhances the sensation of hunger- something that’s more pronounced in children. The growth and development of children also gets disrupted, since sleep patterns affect the release of growth hormones. 

Sleep debt can even be related to glucose metabolism, insulin resistance, inflammation and, most perniciously, belly fat. That’s the fat that accumulates around our organs, causing all sorts of problems, and leads to lifestyle diseases like immunity problems, diabetes, heart disease, and cancer.

Regular exercises who don’t get enough sleep should know that sleep debt is believed to decrease protein-building, and possibly increase protein breakdown, which counter-productively favours the loss of muscle mass and hinders muscle recovery after damage induced by exercise.3

While the cause-and-effect of these associations still needs to be studied further, it’s clear enough that sleep debt can be disruptive to one’s lifestyle and health goals, to say the least. 

Here’s what we can do, though.


1] Relax before bedtime

Any sort of cognitive stimulation (even things like watching a movie or your favourite TV show) keeps the brain active, which is the exact opposite of what it should be. Fretting, which can stimulate the stress hormone, cortisol, will also keep a person up.

It’s important for us to identify ways to relax and use the most effective technique before bedtime – whether it’s a warm bath, soft music, easy stretches, deep breathing or relaxing sounds. Anything that gives the brain a break.


2] Keep the lights turned off

A hormone called melatonin induces sleep by making us drowsy. This hormone is suppressed by light, which then disrupts the sleep cycle.4 This is also a reason to sleep at night (as opposed to during the day) for better sleep quality.


3] Get the Right Nutrition

Some studies suggest that eating larger quantities of protein and fat in the day, and more carbohydrates at night, can result in better sleep – but there’s a lot of variation and contradiction in these studies, so we’d suggest just sticking to whole grains as a carbohydrate source for anyone who plans to follow this, to avoid a peak in blood sugar at night.

When it comes to vitamins, minerals and other nutrients, however, here are specific links we need to be aware of:

– Vitamin B deficiencies, especially vitamins B12 and B6, have been linked with sleep problems. Vitamin B12 is found naturally in animal products (such as meat, fish, eggs, and dairy), while sources of vitamin B6 are meat, fish, leafy and root vegetables and some fruits (eg. bananas, pineapples, and avocados).

– Vitamin D3 improves sleep quality by affecting the part of the brain responsible for sleep. This can be found in mushrooms, red meats, eggs, fatty fish and cheese, and from sunlight.

– Experts consider there to be a relationship between sleep and our magnesium and calcium levels. Foods high in these minerals include dark leafy greens, nuts, seeds, fish, beans, whole grains, avocados, dairy products, bananas, and dried fruit, to name a few.

– Taurine is supposed to have a relaxing effect on the body. You can find this amino acid in eggs, seafood, red meat and supplements.

– L-theanine improves sleep quality, but it is found in tea (which has caffeine). So, decaffeinated green teas, especially ones that contain camomile and ginseng, may be helpful.6

Above all- we must favour and prioritise our sleep time. Humans are creatures of habit, which makes it important to gradually set up a routine where we get at least 6 hours of sleep daily. Let these evidence-based facts remind us why it’s needed.



1. Leger D, et al. Molecular and Cellular Endocrinology.
2. Van Cauter E. Diabet Med 2011, 28(12): 1455-1462.
3. Dattilo M, et al. Med Hypotheses 2011, 77(2): 220-222.
4. Chepesiuk R. Environmental Health Perspectives 2009, 117(1): A20-A27.
5. Peuhkuri K, et al. Nutrition Research 2012, 32(5): 309-319.
6. Bryan J. Nutrition Reviews 2008, 66(2): 82-90.

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