By now, most of us have absorbed the idea that sleep is important. Very important. During the roughly one-third of our lives that we spend with our head on the pillow, the brain stores memories and processes information, it cleans out waste products that accumulate during the day and it signals growth hormones to repair and rebuild the body’s tissues – all while we’re conveniently asleep! No surprise then that people who get a full, deep night’s sleep – on a regular basis – are much healthier, on average, than those who don’t. So if you want to sleep better and improve your health at the same time, here’s a topline on how to use light, to help you take back the night – and snooze happily through it:

Light and dark are key signals for your body.

OK, so, sleep is essential – it almost goes without saying. But what might not be so obvious is the role that light, actually light and dark, play in ensuring that good night’s sleep. It turns out that sleep, like most of our other physiological functions, runs on a clock and that clock is set by our exposure to light.

Those signals come in through your eyes.

Special cells in the retina of the eye register the amount of light that comes in and send that information to a “master clock” in the hypothalamus region of the brain which in turn regulates the running of the whole body. Exposure to strong light, especially strong outdoor light in the morning, revs up our metabolism, as in, “we’ve got things to do today.” And the research suggests that the more alert we feel during the day -- “lit up,” if you will – the easier time the body has shifting to nighttime footing, when low light levels help slow the body down and ready it for sleep. In one University of Illinois study, office workers who worked near windows rated their sleep quality as better than their colleagues who toiled in artificially-lit windowless environments. (Unfortunately, indoor lighting provides only a fraction of the light intensity of the sun.)

Uh, what time is it?

If strong light exposure during the day is key to a good night’s sleep, at night, the scenario flips. In the evening, low light is your ticket to sound sleep -- bright light basically tricks your body into thinking it’s still daytime. All that light at night tamps down the body’s production of melatonin, the ‘sleep hormone’ that prepares us for sleep, making us feel drowsy, relaxing the muscles, lowering the body temperature. For most of the time humans have been on the planet, low light exposure in the evening was just a fact of life but the invention of the electric light bulb changed that. Then, in recent decades, the screens that have come to practically define modern life – TV, computer, smart phone – bathe us in electronic light for most, if not all, of our waking hours. Great for being perpetually in touch with ‘breaking news’ but crappy for sleep.

Light at the wrong time can make sleep but a dream.

With our all-light all-the-time lifestyles, the result is, our bodies’ internal clock gets knocked out of synch. We don’t get the undisturbed, restful sleep we need, especially the REM sleep that’s important for mood and memory. We wake up groggy and grouchy, like having a permanent case of low-grade jet lag. (Regular travelers appreciate that crossing time zones on long flights is the easiest way to screw up the light-sensitive “sleep/wake” cycle.) But it’s the long-term effects of poor sleep that should concern you the most. There’s a raft of studies that show that night shift workers, who have to fight their “circadian rhythms” to do their job, suffer much more heart disease and cancer – which is one of may reasons why I am always after my patients to clean up their sleep acts and focus on doing everything they can to do it better. It’s that important!

Adjust your light tonight!

Here’s a short list of ways to make light your sleep ally, not your sleep enemy. To get started, re-think your approach to day and night and make them work for you:

• Get plenty of natural sunlight during the day. Especially if you have to work in a windowless office, take a couple of walk breaks, for instance, first thing in the morning and at lunch, to absorb that energizing, and sleep-stabilizing, radiant energy. You’ll likely go to bed and get up earlier, the body’s optimal setting.
• “Power down” an hour or two before bedtime. Disengage from the TV, the computer and the phone; and lower the light levels in the house, using a dimmer or turning off non-essential lights.
• If you do a lot of work on screens in the evening, use devices that have a “night mode” that helps tame the blue light frequencies which melatonin is most sensitive to.
• Keep the screens out of the bed. If you like to read before falling asleep, an old-school print book, lit with a small night-light, is your best bet. If you must use a laptop or a tablet, buy a pair of amber-tinted “blue blocker” sunglasses to, you guessed it, block the blue light frequencies, and read with a night-light rather than a pitch dark room to help ease eyestrain.
• When you turn in for the night, keep the bedroom dark. I mean, really dark, no glowing clocks or phones in your face. If you’ve got street light or early morning sunlight seeping through the bedroom window, invest in heavier shades or curtains, if necessary, “blackout curtains.” Put black tape over blinking surge-protector lights and any other appliance that send beams of light into the room no matter how tiny they may be. If light is still leaking into the bedroom, consider an eye mask. They can take a little getting used to but as long as you buy a soft, comfortable model, they’ll work.
• Make use of those little plug-in night lights – the very low light, red-colored ones are easiest on your melatonin – you need just enough light to light up a nocturnal path to the bathroom. And use one to keep the bathroom (barely) lit as well. Nothing worse than flipping on the light switch and having your bathroom lit like an interrogation room.