“Sleep is your superpower” — sleep scientist Matt Walker

You prioritize eating well, working out, and drinking lots of fluids, so why is your weight loss or fitness regime not making progress? It’s possible you’re not getting enough sleep—after all, sleep isn’t just important for the mind, but the body as well. Even if you do everything you can during the day to lead a healthy life, if you suffer from low-quality sleep, it can be difficult to maintain the energy and motivation needed to fulfill your goals to the best of your ability.

But don’t take our word for it; plenty of scientific studies chronicle the importance of a good night’s rest.

How Much Sleep Do I Need Each Night?

This is somewhat of a tricky question. Although it’s recommended that adults get between 7–9 hours per night, these figures can vary significantly based on certain factors, such as how much you exercise. Sports medicine specialist David Geier, MD compares the extra sleep needed by athletes to increased calorie consumption.

So if you work out often, it’s likely you’ll require more sleep per night, or even short naps during the day. Even if your exercise regime is on the mild side, you may find that you need slightly more or less sleep than the recommended amount. It all comes down to your unique physiology. Still, it’s important not to deviate too far from these figures—that’s when the problems start to pop up.

Effects of Sleep on Mental Health

In recent years, the importance of mental health has come to the forefront, and here too studies have found sleep to play a significant role. Aside from lack of sleep causing many people to wake up on the “wrong side of the bed,” it turns out sleep’s effects on mood and mental health are even more dramatic than some might suspect.

One longitudinal study assessed adults ages 21–30 and found that, compared to those with common sleep habits, those with insomnia were four times more likely to develop major depression based on a follow-up interview conducted three years later.

And it’s not just depression; symptoms of anxiety disorders like PTSD are also known to be adversely affected by insomnia. A review from 2015 concluded that sleep disturbance has the potential to stimulate the mechanisms that “promote the pathophysiology of PTSD.” Even those who don’t suffer from these conditions will invariably find themselves operating below their full potential when deprived of sufficient sleep.

Effects of Sleep on Exercise and Recovery

Have you ever had a little too much fun over the weekend, only to flounder at the gym come Monday? Aside from anything you may have consumed in excess, how much sleep you receive sustains a huge impact on exercise performance and recovery. A 2006 study published in Physiology & Behavior concluded that “Compared to those who have been deprived of sleep alone, individuals that performed 5 h of intermittent moderate exercise during 30 h of sleep deprivation appeared to be more vulnerable to negative mood disturbances and impairment in reaction times.”

Sleep is the time when muscles grow and repair themselves, so no matter how much you work out, if you’re not getting enough sleep, you’ll likely find yourself staying in a rut until you change your habits. Even an hour of extra sleep per day may be enough to give you the stamina and energy you need to improve month after month.

Effects of Sleep on Hormones and Weight Loss

Just like exercise, weight loss goals can be seriously hindered by bad sleep patterns. Not only are levels of hunger-inducing hormones leptin and ghrelin affected by sleep, but also insulin. Increased levels of insulin are known to contribute to fat storage and the risk for type 2 diabetes, a condition affecting up to 9.4% of Americans. Moreover, growth hormone, testosterone, and cortisol levels are all impacted by poor-quality sleep.

The above represents a snapshot of the many ways in which sleep affects different facets of our lifestyle. Sleep also plays an important role in cardiovascular health, skin restoration, and immune health, among numerous other functions. No matter if you’re an amateur athlete, trying to burn fat, or struggling with your mental health, there’s no doubt that getting sufficient sleep should be very high on your list of priorities.