woman sleeping
woman sleeping
(Image credit: Voisin/Phanie/REX/Shutterstock)

If a high-intensity workout regime and kale-based diet sounds, on balance, a bit too much like hard work, you're going to love the latest scientist and trainer-backed approach to shedding those unwanted pounds: sleeping. Not convinced that how well you sleep affects your weight? In one study, those who spent 4 hours a night between the sheets over 5 consecutive nights gained almost 2lbs more than those who took to their beds for 10 hours, over the course of a week. Read on to discover how you could lose weight while you sleep.

Why is sleep so important?

Not getting enough sleep can derail your attempts to lose weight for a number of reasons:

1. When we're sleep-deprived, we tend to feel sluggish and lacking in energy. The result? Our bodies encourage us to seek an alternative source of energy: food.

"Feeling sleepy can create the urge to eat something to boost energy and stay awake. It kicks the digestive system into having a job and keeping awake," says Torey Armul, a spokesperson for the Academy of Nutrition and Dietetics. If you think you're craving energy, rather than calories, get an early night, and try to sneak in a nap if you can.

2. Our bodies treat sleep deprivation as a threat, sending us into 'survival mode'.

The effects are threefold: (a) our appetites increase in order to encourage us to take in more energy to deal with the threat (b) our metabolisms slow down in order to conserve resources (c) stress hormones encourage us to store stubborn fat, particularly around the midsection

"Cortisol is our fat-storing hormone," says Joe Wicks (a.k.a. The Body Coach). "If this is elevated through stress or tiredness, it's going to be a lot harder to shift those extra pounds. Getting a good night's sleep really helps to bring this down."

3. Sleep deprivation is associated with food cravings.

A meta-analysis of 11 studies found that those who slept for 4 hours a night consumed, on average, 385 more calories the following day (equivalent to a medium portion of McDonald's fries) than those who slept for at least 7 hours. Sleep-deprived research participants also tended to pick calorie-dense fatty foods over healthier protein-based choices.

4. Sleep affects how our hormones function.

When you sleep well, levels of ghrelin (the 'hunger hormone') plummet, whilst leptin (the 'satiety hormone') rises and insulin sensitivity improves. In one study, healthy participants who slept for 4.5 hours a night demonstrated a level of insulin resistance comparable to Type 2 diabetes patients after just 4 days.

How can you 'sleep yourself slim'?

1. Use your waking hours well

Unfortunately, sleeping for 12 hours doesn't give you a free pass when it comes to diet and exercise. But swerve the sugary snacks, start building lean muscle and get your heart pumping with a quick metabolism-boosting workout and you'll start burning fat with your eyes shut - literally.

"Do really short, intense workouts and eat quick, healthy meals," Joe Wicks recommends. "You can then lose weight while you sleep - regular exercise and feeding your body with the right foods will mean it will keep burning calories while you are resting."

2. Practise good 'sleep hygiene'

Improve sleep quality by avoiding caffeine after 2pm, limiting screen time after dinner and sleeping in a blacked out room.

"Learn how to switch off," says Joe. "Little things like not having a TV in the bedroom and staying away from your phone too close to bedtime really help. I listen to Magic radio and have an infuser by my bed - I might sound like an old man, but I fall asleep straight away. It also means I wake up with bags of energy."

Discover more things you can do to promote weight loss while you sleep.

3. Get it where you can

If you can't manage 7 hours every night, don't panic - it's counter-productive. Simply squeeze in a weekend nap, or make an effort to get an early night the following evening.