The best light for sleeping is a lightless environment, that is, a state of complete darkness. However, in situations where nighttime lighting is needed (such as getting up at night), warm-toned, low-intensity red or amber light will interfere with sleep the least. Here are the scientific basis and specific suggestions:
1. Why is complete darkness the most ideal?
Melatonin secretion: Darkness stimulates the pineal gland in the brain to secrete melatonin (sleep hormone), while light (especially blue light) inhibits its secretion.
Biological clock regulation: A dark environment helps maintain the natural circadian rhythm (biological clock) and avoids sleep disorders.
2. If nighttime lighting is required, the scientific reason for choosing red light/amber light:
Wavelength sensitivity: The photosensitive cells in the retina (ipRGC) are most sensitive to short-wave blue light (400~500nm), which strongly inhibits melatonin. Long-wave red light (>600nm) has little effect on it.
Research support: Experiments at Harvard Medical School show that the inhibitory intensity of red light on melatonin is only 1/100 of that of blue light, and it does not significantly delay the time to fall asleep.
3. Types of light to avoid:
Blue light and white light:
Sources: LED lights, mobile phone/computer screens, cool white light bulbs (color temperature>4000K).
Harm: Inhibits melatonin secretion by more than 50%, delays sleep and reduces sleep quality.
Strong light: Even warm light, too bright will interfere with sleep (recommended brightness <10 lux, equivalent to candlelight level).
4. Practical suggestions:
2~3 hours before bedtime:
Use warm-colored lamps (color temperature ≤2700K) and turn down the brightness.
Turn on "night mode" (filter blue light) on your mobile phone/computer, but it is best to reduce its use.
Bedroom environment:
Install blackout curtains to eliminate external light sources (street lights, car lights).
Turn off the indicator lights of all electronic devices (cover with tape).
Night lighting:
Choose a red or amber night light (such as a salt lamp) and place it low to the ground to avoid direct sunlight into the eyes.
Avoid using white or blue night lights.
5. Special scenarios: night shift workers
Night work: Exposure to bright white light (simulated daylight) can keep you awake.
Make up for sleep during the day: Use a blackout eye mask + earplugs, and keep the bedroom completely dark to promote melatonin secretion.
The best sleeping environment = complete darkness
Lighting when necessary = low-brightness red light/amber light (wavelength>600nm, brightness<10 lux)
Little knowledge: For millions of years before the invention of electric lights, humans relied entirely on natural light-dark cycles for sleep. The artificial light that modern people are exposed to at night, especially blue light, is essentially "light pollution" unprecedented in the history of evolution. Adjusting the light environment is actually helping the body return to its familiar original rhythm. you can know more red and warm white light on https://www.benweilight.com
