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Why you need a good night’s sleep to get fit

Regardless of your fitness goals, getting enough sleep is really important for overall health and wellbeing. Making it a priority to get good quality sleep can hugely impact the results we see from our workouts.

Why sleep is so important

Extensive research from 2004 discovered that ‘whether it’s building muscle or losing body fat, sleep is paramount’, so get as much as you can, whenever you can.

There are various reasons why sleep is so beneficial. Scientists based at Chicago University revealed that one of the main benefits is due to hormones. They found that inflated stress caused by lack of sleep placed a ‘hormonal handicap’ on the body which negatively affected their subject’s fat loss. In 1994, scientists discovered a hormone called leptin, made in the small intestine, which helps to regulate energy and has fat regulating properties.

Chicago University researchers took 12 healthy men aged from 22-30 and monitored calorie intake and appetite during two days of ‘extended sleep’ and two days of ‘restricted sleep’. They discovered that when subjects were restricted to only four hours of sleep, their leptin levels dropped by 18%. This in turn increased their appetite by 23%. So in layman’s terms, leptin is the signal to your brain that makes you feel full and lack of sleep means lack of leptin.

Tired people want more carbs

Scientists involved in the study agreed that subjects with ‘restricted sleep’ not only had a larger appetite, but craved ‘Calorie dense food with high carbohydrate content’. Enter ghrelin or, as we like to call it, gremlin – the hungry hormone. This is the hormone that sends a signal to your brain that you need food and in the ‘restricted sleep group’ this hormone was at times 30% higher.

Hormones tend to work in tandem with each other, so the best way to imagine this process is like a tug of war between leptin and ghrelin. Leptin is telling you that you are full and ghrelin is telling you that you need food – fast.

The more you sleep, the more leptin you make, so effectively, the more you sleep the less hungry you will be. To quote the Journal of Neurochemistry ‘Leptin is the central control for our appetite behaviours’, if we are able to control our appetite then it makes it easier to control our overall caloric intake’.

How much we sleep matters

In 2010, scientists took 20 overweight, middle aged, moderately healthy test subjects –  half of which slept for 5.5 hours a night, the other half slept for 8.5 hours per night. They did this for 3 months and then swapped conditions and completed another 3 months.

All subjects had a near identical calorie consumption of (1450 kcal). Their daily calorie expenditure was also the same, approx. (2140 kcal) which is equal to a (700 kcal) calorie deficit.

Both groups lost about 3kg during the study, but subjects that slept for 8.5 hours lost 50% fat and 50% muscle mass, whilst subjects that slept for 5.5 hours lost 20% fat and 80% muscle mass. Remember that lack of sleep causes ghrelin to spike, so not only did the test subjects lose less body fat and have less sleep, but they were also far more hungry.

Sleep is also our recovery tool and it’s imperative in regards to muscle growth. When we sleep, we grow and repair. When muscles are put under stress, regardless of the stimulus, it causes ‘micro trauma’, which means lots of little tears across the muscle fibre. It’s when you sleep and recover that these small tears repair via a process called protein synthesis and as long as you have an energy surplus which includes enough protein, then this process in turn creates bigger and stronger muscles.

Sleep helps your mental, too

In the words of the Dalai Lama “sleep is the best form of meditation.” There are so many biological, physiological and psychological factors at play in terms of how, what and why we eat food that it is difficult to neglect the fact that the stronger and more stable mindset we have, the better we will be able to adhere to any fitness goals we set.

We must remember that the fundamental reason behind choosing to ‘get fit’ is essentially to improve our happiness. Whatever our goal may be, if we are not happy then it is not worth it. Therefore, we must get enough sleep to rest our mind, relieve stress and allow ourselves to rejuvenate properly each day so we can be happy.