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This is a quick overview of the problems with light at night and how to keep yourself healthy.
You will be able to answer the following:

1) How is light at night harmful?
2) Why is darkness at night crucially important to your health and well being?
3) What is it about blue light in particular that is so harmful?
4) What can you do to take control of your light exposure and your health?


We all know the importance of getting enough sleep. But do you know about the importance of getting enough darkness? Sadly, most people do not. There is currently a flood of new research into just how powerfully light affects our biology. It turns out that the light/dark cycle is crucially important for the synchronization and timing of numerous biological processes. You can think of it as two separate states: Daytime Physiology and Nighttime Physiology. Daytime physiology has distinctive hormonal attributes that are different from nighttime. In the daytime you are primed for physical activities, eating, and are more robust on a cellular level. At nighttime (or should I say “dark-time”) your body shifts into repair and restoration mode. One of the hallmarks of nighttime physiology is the hormone melatonin. Most people are aware that melatonin aids in falling asleep but it is a very complex hormone with a HUGE range of effects on the body including powerful antioxidant activities and cancer suppression. Only in darkness can your pituitary gland produce healthy amounts of melatonin.

Light at Night

Laptop on BedLAN (Light At Night), also know in the literature as ALAN (Artificial Light At Night) has become an epidemic in our industrialized world. Every week, it seems, new studies are emerging that implicate circadian disruption as a major contributor to the diseases of modern civilization. Everything from obesity and metabolic syndrome, to breast cancer and heart disease can be traced back to circadian disruption. The research has also implicated blue light as the most disruptive wavelength of light. Blue light exposure at night wrecks havoc on the circadian rhythm. Your body is masterfully tuned to calibrate the time of day. It does this through special photo receptors in the eye that monitor light intensity and wave frequency. These receptors are specifically tuned to detect light on the blue end of the spectrum. In nature, blue light is abundant in the daytime and virtually nonexistent at night. Of course in the modern world it’s not so simple…

Blue Light

The absence of light, especially light in the blue spectrum, is how you body knows that it’s night. Exposures to blue enriched light at erratic time intervals confuses your biology and inhibits the smooth transition into nighttime physiology.

So where is all this nighttime blue light coming from? Screens and energy efficient lighting!
Unfortunately our most precious tech gadgets stream blue light directly into your eyeballs. If that’s not bad enough, fluorescent and LED lamps also emit vastly more blue light than regular old fashion incandescent bulbs. Even if the color looks like the same “soft white” as your old bulbs, the spectrum has a sharp peak right in the most stimulating wavelength range. Light at night in general can negativity impact your biorhythm and melatonin production but there is a relatively small portion of the spectrum that is far more stimulating than the rest.

Image Credit: https://en.wikipedia.org/wiki/User:gringer?rdfrom=commons:User:Gringer

What to do?

The magnitude of contrast between night and day drives circadian biology. Bright sunny days and dark nights on a stable schedule is the ideal. Your clock is designed to be flexible, adapting to seasonal variations and varying levels of light due to weather, terrain, etc.. What it is not designed for is modern light exposure patterns. Your biology doesn’t cater to your workweek and weekend schedule differences. Unfortunately it’s not designed to handle bright light, food, and drink at 12am on Saturday night and being asleep by 10pm the next day. Stability is the key. Of course this is not so practical in modern times. That why this site exists! Here’s a brief summery of what you can do:


  • Get as much natural light as possible
  • Crank up the brightness and color temperature as much as you can indoors
  • Spend time outdoors, nothing beats the natural full spectrum light of our sun

Sleeping environment

  • Get yourself some quality blackout curtains
  • Tape over all the annoying LED lights in your room
  • Keep your bedroom cool


  • Use low wattage incandescent lights or orange LED or CFL lamps
  • If you need nightlights get red or orange ones
  • Task lighting rather than overhead lighting
  • Orange glasses at least while using electronics (even if using f.lux!)

Quick Start

The first thing that I recommend is to get your self a pair of good quality orange glasses and challenge yourself to wear them at the same time every night for 5 consecutive days. You will be happy you did!

See the articles and guides on this site for more a lot more information and tips. Back to Top ↑

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