Why sleep is vital to your mental health.

Bed with white sheets

Why would humans evolve to spend one-third of our lives unconscious and therefore vulnerable? What could be so important about sleep that every mammal is tethered to sleep more tightly than any other rhythm in nature?

It’s because there is no other form of self-care that affects our mental health — indeed our overall health — as much as sleep. And it’s not even close.

1. Sleep improves your mood. We’ve all suffered the effects of a single night of poor sleep and felt emotionally fragile, irritable, or moody. The opposite is also true: With just one night of great sleep, we can feel like a million bucks.

Improving sleep is the first, and sometimes only, step needed to begin recovering from mood or anxiety disorders. Research confirms that easing insomnia doubles the chances of recovering from depression. It is equally important in preventing depression in the first place.

2. Sleep keeps your mind sharp. When you stay up late working on something important for the next day, does it go well? Sleep research is clear on this: Deep sleep is crucial for storing and retaining memory and creative thought. You are far better off “sleeping on it” than pulling an all-nighter.

3. Sleep repairs your body. Systemic inflammation appears to be a common thread in heart disease, dementia, chronic pain, depression, and other conditions. Deep sleep tamps down inflammation, allowing your body to restore and heal itself. It also helps regulate metabolism, making it a key player in managing weight.

How to Sleep Well

With rare exceptions, seven to eight hours of sleep per night is the sweet spot. I fought that idea for years before finally accepting that getting enough sleep is perhaps the most protective thing I can do for my health. Too much sleep, on the other hand, is likely to leave me feeling thick-headed.

If you’re like me, the solution is pretty simple: Admit how important sleep is and start making it a priority. For some people, though, getting quality shuteye is not that easy.

Setting yourself up for a good night’s sleep starts first thing in the morning. It’s all about circadian rhythm, and that means training your body to get up at the same time every day — including weekends (though sleeping in for up to an hour longer than usual is OK).

Exposing yourself to bright light in the morning, either from the sun or a light-therapy device, helps set that pattern. You’ll also improve your sleep if you exercise early in the day and engage in spurts of activity all day long.

Remember that there is a rhythm to the day, and nature wants you to unwind in the evening. That means not taxing your digestive system with a large, heavy meal too close to bedtime. Your body has to work all night to digest it, and that’s not conducive to deep sleep.

Neither is late-night consumption of alcohol; it’s better to have your glass of wine with dinner.

And so long as sleep is an issue, cut out caffeine entirely. It may interrupt your sleep no matter what time of day you drink it.

Another key is nighttime light exposure. About two hours before bedtime, dim the lighting in your home to allow for melatonin release; it will make you naturally sleepy. This also means turning off your personal electronic devices and, above all, not working in the late evening.

Sleep on it instead.

is an integrative psychiatrist and the author of The Chemistry of Joy, The Chemistry of Calm, and Staying Sharp. He is the cofounder of

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