The Benefits of Sleep On Health

Sleep makes you better, but its importance goes way beyond just boosting your mood or banishing under-eye circles. Peta Bee is a health and fitness journalist writing for The Times, Sunday Times and Irish Examiner, and co-author of the 2014 bestseller Fast Exercise.

In recent years, scientists have been rigorously investigating what happens when we sleep and how our minds and bodies react to getting too little – or indeed, too much – shut-eye. What they’ve discovered is that not only is sleep is as important as food and physical fitness when it comes to longevity and wellbeing, but that the three are intertwined and impact each other in ways we are only beginning to understand.

 Here is how experts think the three pillars of health work synergistically to keep us at our best:

Sleep and Diet:

Sleep and your waistline: Dozens of published studies have shown that the disrupted sleep cycles of shift workers can lead to poor diet, metabolic problems and weight gain. And the scientific consensus is that adults who sleep for less than five or six hours a night are more likely to be overweight. Five years ago, a study at the University of Colorado suggested that missing just a few hours of sleep for several nights in a row could lead to almost immediate weight gain. There’s no single reason why this happens, but evidence points to behavioural changes we make when we skimp on sleep – we eat more of the foods we shouldn’t such as sugary and refined carbohydrates and fatty, processed foods.

Good sleep foods: When it comes to improving your sleep through diet, there are lots of steps you can take. There are the more obvious actions – avoiding stimulants, such as caffeine, sugary drinks and too much alcohol within a couple of hours of bedtime – but also more unexpected dietary tweaks that can enhance your sleep. One study in the American Journal of Clinical Nutrition found that eating higher-glycaemic carbohydrates such as jasmine rice or breakfast cereal around lunchtime can halve the time it takes to fall asleep because these foods increase the amount of the sleep-inducing hormone tryptophan in the blood. The Sleep Council, a trade body, once recommended “sleep sandwich” of banana (rich in magnesium and potassium, which help relax muscles), Marmite (rich in B vitamins, which assist the release of tryptophan in the brain) and lettuce. Failing that, try eating kiwi fruit, rich in the relaxing hormone serotonin, an hour before bedtime. They have been shown to help people nod off more quickly.

Sleep and Exercise:

Anyone who has tried to do a workout when they are feeling groggy through sleep deprivation will tell you how sleep impacts exercise capabilities. I know from experience that my daily run becomes far less enjoyable when I’ve missed any of my valued nightly sleep. I wake up tired and less motivated to exercise and when I drag myself out of the door, the run feels a slog and, invariably, I run more slowly than usual. I am not alone. Sleep is considered a performance enhancer among today’s exercise scientists. Elite athletes and their coaches invest huge amounts of energy, time and money into ‘sleep hygiene’, making sure that pillows, mattresses and bedrooms provide an optimal sleeping environment. And it’s not just that it provides a psychological boost:

Sleep and Sports Performance: 

There’s little doubt that missed hours of sleep can cost top athletes dearly. A few years ago, Dr Cheri Mah, a researcher at Stanford University’s sleep disorders clinic, analysed the sleep/wake patterns of five female athletes over three weeks and then asked them to perform a series of athletic tests that included sprinting, tennis serves and other drills. On average, the women were getting between six to eight hours’ sleep a night, which, considering their intensive training, was too little for them to fully recover. When the same subjects were asked to sleep for up to ten hours per night, their performance in the drills improved significantly and they were able to run faster, hit tennis balls more accurately and exhibit greater arm strength. This isn’t to say that you need ten hours sleep if you go to the gym, but it demonstrates just how much sleep aids recovery of muscles and mind after sport.

The Hormone Connection: 

During deeper sleep, the pituitary gland produces human growth hormone (HGH) which is essential for the recovery process, helping to repair muscles after exercise. If you get too little, it sleep means the body produces less HGH and more of the stress hormone cortisol that has the opposite effect.

Sleep and Body Repair:

Sleep is the time when the body is primed for recovery and your muscles being to re-build and strengthen after exercise. Some scientists have suggested that eating protein after a workout and before bed will help this process. A pot of yoghurt 30 minutes before bed is idea as the protein it contains, almost entirely casein, is slowly digested by body. In 2012 a study published in the Journal of Nutrition showed how consuming casein after a strength workout and half an hour before going to bed stimulated muscle protein synthesis overnight much better than a placebo.


There is a huge amount of interplay between these factors and there is mounting evidence that good sleep is important for so much more than avoiding tiredness. Get enough shut-eye and you could find that your waistline and fitness start to improve. It certainly works for me. I eat more mindfully and exercise harder after getting enough sleep. And that, for me, means the early nights are worth it.

What Peta has to say:

We once thought there were two main factors for staying healthy: diet and exercise. How active we are and what we eat on a daily basis are known to have a profound effect on our ability to ward off disease, to stay slim and to remain positive in our outlook on life. But an additional factor is now firmly established as a third pillar of good health: sleep.


I’ve long realised that sleep is invaluable to my own health and mood. When I do miss my regular eight hours, I am inclined to let my nutrition and exercise habits slip the following day. Only when I am tired do I head for the biscuit tin or contemplate slumping on the sofa instead of hitting the footpaths and trails around my home. And science seems to back up my low levels of motivation.

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