Dim light, sleep tight: How to use light and darkness to optimize sleep


Feeling sleepy? You’re not alone. More than a third of Americans aren’t getting the recommended minimum of seven hours of sleep per night, and on average we get a full hour less sleep than we did 60 years ago. This has far greater implications than simply feeling tired and cranky or needing that extra cup of coffee to keep yourself going. Inadequate sleep has been linked to obesity, heart disease, diabetes, impaired cognitive function, depression, and many other health problems. 

For millennia, our bodies have been governed by circadian rhythms set by the rising and setting of the sun. We are hard-wired through millions of years of evolution to wind down in the evening and go to sleep soon after dark. Modern society has disrupted this natural pattern, and man-made light is partly to blame. Research has shown that nighttime light exposure suppresses the production of melatonin, the hormone that controls sleep and wake cycles. This can be disastrous for sleep quality. 

For thousands of years, humans were exposed to bright light from the sun throughout the day, while the night had only the warm yellow glow from fire and candles. Sixty years ago, we had plenty of light at night, but homes were mostly lit with warm-spectrum incandescent bulbs. TV, phone, and computer screens, on the other hand, emit blue-spectrum light, which suppresses melatonin much more than warmer light. In many homes, incandescent bulbs have been replaced with more energy-efficient fluorescent or LED bulbs, which emit considerably more blue light. All this blue-light exposure sends the message to our brains that it’s daytime and time to be awake.

When TV became widespread, there were only a handful of channels, and most signed off at night. Today, we have infinite digital entertainment available 24 hours a day. If there’s nothing good on TV, you can watch something on Netflix or YouTube. There’s always Facebook, Instagram, Twitter, or Snapchat to keep up with, strangers to argue with, and cat videos to watch. All this temptation makes it much more difficult to get to bed at a decent time. This constant online entertainment keeps us up later, while bathing our eyes in a constant flood of blue light. This has contributed to an epidemic of poor sleep, insomnia, and chronic sleep deprivation.


  • Getting bright light exposure before noon increases the production of serotonin, a precursor to melatonin, and helps optimize our circadian rhythm. A walk outside before work or at lunchtime (without sunglasses) can make a big difference at bedtime.
  • Make your bedroom a pitch-dark space. Get rid of any glowing clocks, night-lights, and anything else that has a light. Even tiny lights, like those on a power strip, can have an effect on melatonin; these can be covered with electrical tape. Get blackout shades for your windows if light comes in from outside. 
  • Choose warm-white bulbs for lights in your bedroom and other rooms where you spend time in the evening. You can even replace regular bulbs with orange bulbs for a cozy, firelight ambiance. I have an orange LED nightlight in my bathroom so I don’t have to turn a light on when I get up during the night. 
  • Use your phone’s settings or an app to automatically change the color of your screen to a warmer hue, which will reduce the amount of blue light getting to your eyes. You can also do this on your desktop or laptop with a free app called f.lux
  • Geek out and try orange glasses! If you want to watch TV or can’t keep off your devices, blue-blocker glasses can, as the name implies, block blue light and prevent melatonin suppression. You can buy blue-blocker glasses for less than $10
  • This is a tough one: turn off your devices in the evening. Most of us are hopelessly addicted to our phones or tablets, and the urge to check your email one last time or see if anyone commented on your Facebook post is powerful. This not only exposes you to blue light, it also stimulates your brain much more than something more passive such as reading a book. Before bed, you want to be winding your brain down, not firing it up! 
  • Set an alarm 60 or 90 minutes before bed to remind you to turn your devices off or put them away. Keeping them out of the bedroom can also reduce temptation.

Sleep well, everybody!