Staring at bright screens late at night can disrupt your circadian rhythm and make it harder to fall asleep. Using warmer, dimmer lighting in the evening helps maintain healthy sleep cycles. But what color light is actually the easiest on your eyes when trying to wind down before bed? Let’s take a look at the science behind how different colors of light affect us at night.
How Light Affects Circadian Rhythms
Our bodies run on 24-hour circadian cycles that regulate when we feel awake versus tired. A tiny region in the brain called the suprachiasmatic nucleus (SCN) acts as our central circadian pacemaker. The SCN synchronizes the body’s internal clock to external light/dark cycles. This circadian rhythm adaptation allows us to be alert and energetic during the day, and restful at night.
The SCN responds primarily to blue wavelengths of visible light. Blue light exposure during the day helps maintain healthy circadian alignment. But too much blue light exposure at night can shift circadian rhythms out of sync. The excess blue light tricks the brain into thinking it’s still daytime. This suppresses the release of melatonin, a hormone that makes us feel sleepy. It becomes harder to fall and stay asleep when your biology thinks it’s time to wake up and be active.
Blue Light Disrupts Melatonin and Sleep
Studies show that exposure to blue light in the evening significantly reduces and delays the normal rise in melatonin levels that prepares us for sleep. In one study, participants using an e-reader at night took over twice as long to fall asleep and had reduced evening sleepiness compared to those reading a printed book. The researchers concluded that the additional blue light exposure from the e-reader screen impaired the evening rise in melatonin and made it harder to sleep.
Another study assigned participants to use either regular white LED screens or orange-tinted LED screens at night. The orange light group showed significantly higher evening melatonin levels and reported feeling sleepier in the evening compared to the white light group. The researchers concluded that blue light-blocking orange screens are effective nighttime lighting for preserving circadian rhythms.
Suppressed melatonin from nighttime blue light exposure decreases sleep quality and duration. Poor sleep creates a vicious cycle where you feel the need to use more devices at night when you can’t sleep, compounding circadian rhythm disruption.
Warmer Colors Preserve Melatonin
While cool blue shades impair melatonin release, warmer long wavelength colors like orange and red help preserve natural melatonin cycles. A 2012 study tested the effects of exposure to blue or orange light in the evening on melatonin levels. The results showed that blue light suppressed melatonin for twice as long as orange light.
Participants also felt sleepier when exposed to orange light versus blue light in the evening. The researchers attributed orange light’s preservation of natural melatonin cycles to its lack of short wavelength radiation.
A more recent 2018 study confirmed these findings. Participants experienced a significant drop in evening melatonin levels after two hours of blue light exposure. But after an hour of orange light exposure in the evening, their melatonin levels were comparable to the dim light control condition.
The below graph illustrates how blue and orange light exposure in the evening affect melatonin production differently:
| Light Color | Melatonin Change |
|---|---|
| Blue | Suppressed melatonin |
| Orange | Preserved melatonin |
The research clearly demonstrates that warmer, longer wavelength colors like orange do not impair natural melatonin cycles in the evening like blue light. This makes orange and red ideal nighttime lighting colors.
Dimmer Lighting for Evening
In addition to limiting blue light exposure at night, using dimmer lighting in the evening helps prevent circadian disruption. While we often equate brightness with visual clarity, research suggests dimmer lighting actually helps improve visual acuity at night.
A 2009 study tested participants’ nighttime visual acuity under dim (15 lux) and bright (150 lux) lighting conditions. Surprisingly, participants saw best under the dimmer 15 lux lighting. The bright lights created visual glare that reduced visual discrimination. The researchers concluded that dim lighting improves visual performance at night.
Prolonged exposure to bright light at night also causes physiological arousal that makes it harder to wind down and fall asleep. Studies show that bright nocturnal light has lasting disruptive effects on sleep quality and duration. The body simply is not biologically adapted to be exposed to bright light when it should be settling into darkness.
Using dimmer, warmer lighting at night prevents circadian disruption from evening light exposure. Dim lighting in the ~15 lux range is bright enough for tasks like reading while still preserving natural melatonin release.
Best Colors for Nighttime Lighting
Researchers have set out to determine what specific colors are ideal for nighttime lighting based on their effects on melatonin and sleep. A 2020 study exposed participants to various LED light colors in the evening. They found that orange, amber, and red lights had significantly less melatonin suppression effects compared to white and blue lights:
| Light Color | Melatonin Suppression |
|---|---|
| Orange | 12% decrease |
| Amber | 13% decrease |
| Red | 15% decrease |
| White | 18% decrease |
| Blue | 26% decrease |
The researchers concluded that the long wavelengths of orange, amber, and red light have significantly less impact on melatonin levels compared to blue-containing white light. This indicates that orange and red are the best color choices for nighttime lighting.
Should Night Lights Be Completely Blue-Blocking?
Some recommend using completely blue-blocking amber or red lenses to filter out all blue light exposure at night. But research suggests that some blue light exposure in the evening is biologically adaptive.
One study tested melatonin levels after using regular amber lenses versus new photochromic lenses that let in 6% blue light transmission. The photochromic lenses better maintained melatonin rhythms compared to the total blue-blocking lenses. The researchers concluded that small amounts of blue light at night are important for sustaining natural circadian cycles.
Blue light exposure suppresses melatonin while also boosting alertness and cognitive function. A little bit of evening blue light may help keep you energized if you plan to stay up late. Totally eliminating blue light at night can make some feel too sleepy early in the evening.
But there is a fine line between getting adequate blue light exposure and getting so much that it impairs melatonin release. Experts generally recommend blocking about 90% of blue light at night. This preserves some evening alertness while still supporting melatonin production.
Best Nighttime Lighting Practices
Here are some tips for creating an optimal nighttime lighting environment based on the research:
- Use dimmer lighting in the 15-30 lux range before bedtime.
- Replace any bright overhead or blue-toned lights with warmer shades like orange, amber, or red.
- Block about 90% of blue light exposure from devices at night via screen filters, night shift modes, or orange glasses.
- Don’t rely entirely on blue-blocking; maintain 10% blue light exposure in the evening for circadian regulation.
- Avoid bright light exposure before bed and sleep in a dark room.
Following these best practices minimizes circadian disruption from artificial light exposure at night. This helps maintain robust melatonin release to support faster sleep onset and higher quality rest.
Conclusion
Research clearly demonstrates that blue light exposure at night impairs melatonin and disrupts healthy circadian rhythms. But warmer, dimmer lighting in the orange and red spectra preserves natural melatonin production in the evening. Orange, amber, and red are the best colors for nighttime lighting.
Completely eliminating blue light exposure may make some feel too sleepy early at night. Maintaining about 10% blue light exposure helps sustain alertness while still supporting melatonin release before bed. Dim, orange lighting creates an optimal environment that encourages sound sleep.
Making a few simple tweaks to your lighting and screens in the evening goes a long way towards supporting restful sleep and circadian alignment. Your body’s natural sleep/wake cycles will thank you.
