Circadian health
What circadian rhythm affects, and how light can help
Your body clock is set primarily by light, and a long list of conditions, from ADHD to jet lag to metabolic health, trace back in part to its timing. Each guide below summarizes the published research for one area and the light-timing it points to, measured in melanopic lux: the light that actually drives your clock.
ADHD
Most people with ADHD run on a delayed body clock. What timed light can and cannot fix.
Seasonal depression
Winter shifts the clock and lowers mood. The dose and timing that make light therapy work.
Weight & metabolism
The same meal spikes blood sugar more at night. How light timing ties to weight and diabetes.
Athletic performance
You are stronger in the late afternoon, and jet lag costs games. How athletes time light.
Shift work
Night work pits you against your own clock. The metabolic and cancer risks, and how to put light on your side.
Insomnia & DSPD
When you cannot fall asleep, the clock may be late, not broken. The evening light limits that matter.
Aging & dementia
Older eyes let in less clock-setting light. How daytime light helps sleep, mood, and sundowning.
Focus & productivity
Bright daytime light measurably sharpens attention. Most desks are too dim to deliver it.
Jet lag
Your clock shifts about one zone per day. How timed light, eastward vs westward, speeds it up.
Depression & mood
Dim days and bright nights track with depression. What large cohorts and light trials show.
Teenagers
Puberty pushes the clock hours later. Why early school clashes with biology, and what light helps.
Immune & long-term health
Your immune system runs on a clock. How a strong day-night light signal supports it.
Wavelength is a wellness and education tool, not a medical device. This page summarizes published research and is not medical advice. Consult a qualified clinician about any health condition or before starting light therapy.