You might be paying close attention to how active you are and what you’re eating, but are you trying to get away with only a survival ration of sleep? Many of us invest time and money on gym membership, and ensuring that we eat healthy, nutritious food. But what effort do you make to ensure you’re getting adequate quality sleep—the activity you spend almost one third of your life doing?

All too often, we don’t give it a second thought—yet sleep, diet, and exercise are all interconnected and critical to our health. We have to pay attention to all 3 areas to win the health trifecta!

Sleep, the great restorer

Just as your phone’s ability to function is dependent on regularly being plugged into the mains to recharge its battery, a person’s ability to function is also impaired if they are not “plugging into the mains” of sleep. Even though it might seem that you are “out of action” during the time you spend asleep, in many ways, the opposite is actually true. Here are just a few of the reasons why slumber is so vitally important.

Sleep is the time when your body’s ability to heal and repair itself is at its most powerful. The release of growth hormone during the deepest phase of sleep stimulates the repair of functioning cells, as well as the creation of new cells to replace old or damaged ones.

Your immune system is strengthened while you sleep. In addition to helping you defend yourself from infections such as cold and flu, sleep helps you fight the illness if you do become sick. Your fever response—which plays a vital role in overcoming infection—is most effective during sleep, which is one of the reasons why it is common for people who are ill to require more sleep than when they are healthy. So if you notice that you tend to catch colds frequently, you might want to consider getting more sleep.

Sleep lets your brain do some “biochemical housekeeping.” Research published in Monitor on Psychology has shown that sleep helps reduce damage to cell membranes in the brain from free radicals, as well as promoting neurogenesis—in other words, the formation of new brain cells. That’s why your mind feels much clearer after a good night’s sleep.

Getting plenty of sleep is a reliable path towards happiness. The connection between sleep and mood has been thoroughly verified through a variety of scientific studies. Most of us have experienced the irritability, stress, anger, and mental exhaustion that is caused by sleeping poorly. By contrast, sleeping deeply and awaking well-rested promotes feelings of happiness, peace, balance and empathy. And it works both ways: Happy people sleep better.

Your risk of cardiovascular disease doubles if you don’t sleep enough. The National Sleep Foundation reports that people over the age of 45 are estimated to be twice as likely to have a heart attack or stroke if they sleep less than 6 hours per night, compared to people who get at least 6-8 hours’ sleep.

What’s more, insufficient sleep may be sabotaging your efforts in the diet and exercise departments. According to a study published in The American Journal of Clinical Nutrition, getting half a night’s sleep was linked to average-weight individuals consuming about 300 calories more the next day, without expending more energy. One conclusion the researchers drew from these results was that lack of sleep put people of a healthy weight at risk of becoming obese.

And if you’re paying more attention to your workout than your downtime, you might be wondering why your gym sessions are not bringing the results you might have been hoping for. A major part of the reason is that while you’re asleep, your metabolism shifts into anabolic mode—when fat is burned to release energy for tissue repair, and protein synthesis takes place.

Have we become a generation of unconscious sleepers?

Yes, of course you are not conscious while you sleep—unless you count your adventures in dreamland. But considering how important it is to our health, why is it that we rarely give the quality and quantity of our sleep a second thought—unless we are having such problems with restful slumber that it is damaging our waking lives?

One possibility is that because we are unaware of the outside world during the time we spend asleep, we can easily forget to give it the priority it deserves.

Especially in light of its implications for calorie intake and recovery from exercise, as well as all the other ways it contributes to our health and well-being, perhaps it’s time to wake up to the importance of sleep!