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In recent years there has been a growing body of evidence to suggest that sleep plays a much more crucial role in our weight than was originally thought. Here we go through some of the most important pieces of research.

Why is Sleep Important to Weight Loss?

1)  Poor sleep is consistently linked to a higher body mass index (BMI) and the consumption of more calories:

In fact, one major review found that short sleep duration increased the likelihood of obesity by a shocking 89% in children and 55% in adults. The reasons that people tend to consume more calories (up to around 500 more calories a day, on average) are many, including tiredness that leads to more inactivity and, hence, more television (which we know is associated with the consumption of more calories). Also we know that the portion sizes consumed tend to be larger in subjects who are sleep deprived. One fascinating study of 16 men showed that those who were severely sleep deprived tended to select bigger portion sizes.

2)  You are more likely to get the munchies if your sleep is poor:

Many studies have shown an increase in appetite with sleep deprivation, and this is explained by the impact of the hunger hormones ghrelin and leptin. When you do not get adequate sleep, the body makes more ghrelin (which makes you hungry) and less leptin (which signals you are full), leaving you hungry and increasing your appetite. Similarly, the body releases more cortisol (the stress hormone) when sleep deprived, and we know that too much cortisol can affect blood sugar levels and, thereby, lead to increased appetite. Some research has even shown that not getting enough sleep makes us more likely to have sugar or carb cravings. According to lead researcher Haya Al Khatib, “Our results suggest that increasing time in bed for an hour or so longer may lead to healthier food choices.”

3)  People who are adequately rested (and get enough sleep) make healthier choices:

It’s much harder to resist tempting food if you are sleep deprived. We also know that the reward centres of the brain (where feelgood dopamine gets released) are more stimulated by food when you are sleep deprived, and this seems to be true even after just one night of poor sleep. Some research suggests that we are also more likely to have a sweet tooth and to crave carbs if sleep is poor – and we know that sugar elimination or reduction is a crucial part of losing weight. The study involved 42 adults with two groups; one of which were trained in the practices of good sleep. Those who followed good habits, and subsequently slept better, showed a reduction in as much as 10 grams of sugar from their diet after a good night’s sleep, and they were also less likely to crave carbs.

4)  Poor sleep could interfere with your metabolism and even your muscle mass:

Your basal metabolic rate (BMR) is the number of calories your body burns when you’re completely at rest. This is affected by your age, weight, height, gender and muscle mass. The research suggests that poor sleep can slow down the BMR, or make the body’s metabolism work less effectively, leaving more un-expended energy to be stored as fat. Incredibly, it also appears that inadequate sleep can lead to muscle loss which, as we know, is not something we want when we are looking to lose weight, since muscle is metabolically active and helps raise our BMR.

5)  Getting enough sleep makes your exercise habits healthier:

A lack of sleep can make you tired and less likely to exercise but, not just that, you also might tire earlier on in an exercise session if your sleep is poor. This means that people tend to stop exercising sooner or their exercise intensity is poor. The converse is true also: those who sleep well tend to perform better in exercise. In one particular study, college basketball players were asked to spend 10 hours in bed each night for a period of five to seven weeks. At the end of the study the players were faster, their reaction times had improved, their accuracy had increased and their fatigue levels had decreased.

6)  Adequate sleep helps prevent insulin resistance:

Incredibly, your cells can become insulin resistant from inadequate or poor sleep. In fact, even just a few nights of poor sleep is enough to cause insulin resistance. We know that insulin resistance is a problem that can lead to diabetes and weight gain. Being insulin resistant means you may have lots of cravings and are more likely to have a ravenous appetite. Excess sugar can overload your system and, when that happens, the excess insulin tells the body to store more calories as fat.

7)  Sleep is closely linked to mood:

Anyone who is sleep deprived will tell you that it can lead to feeling down or even anxious. That’s because, besides just being tired and finding it harder to manage the day-to-day demands of life, poor sleep is actually linked to changes in serotonin levels; serotonin is a neurotransmitter that influences our mood. A study from the journal Sleep found that not getting enough sleep gradually desensitizes serotonin receptors, leaving you more susceptible to disorders such as depression.