Environmental

Artificial light at night / little daylight

Environmental factor.

In practice

It depends on the case; there is no single guideline.

Effect by goal · level of evidence

Circadian rhythm, sleep, and cancer risk

harms Low-moderate study (A)

Review: artificial light at night (screens, night work) suppresses melatonin and desynchronizes the biological clock, and is associated with higher risk of breast and prostate cancer; too little natural light during the day makes it worse. Observational association.

View the study (study) →

In depth

Environmental · Highest evidence: Low-moderate · 1 finding

Findings

Circadian rhythm, sleep, and cancer risk — harms (Low-moderate, study). Review: artificial light at night (screens, night work) suppresses melatonin and desynchronizes the biological clock, and is associated with a higher risk of breast and prostate cancer; little natural daylight makes it worse. Observational association. 26374931

Information, not medical advice. Prescription drugs require a doctor.

Information, not medical advice. Scientific evidence reflects the quality of the studies.