Research

Hormonal

Blue wavelength light is the most efficient stimulus for shifting the circadian system and suppressing melatonin due to its sensitivity in non-rod, non-cone photoreceptors.

Blue light is the most efficient wavelength for shifting your circadian clock. Light therapy devices enriched with blue light are being tested for this purpose, though sufficient intensity white light can also be effective.

LimitedSupportsMEDIUM confidence
These novel nonvisual circadian photoreceptors, which contain the photopigment melanopsin, are most sensitive to blue wavelength light; thus blue light exposure may be the most efficient wavelength to shift the circadian system and suppress melatonin.
Robert L. Sack et al. · SLEEP · 2007

Why this rating

Based on recent discoveries and testing of devices, but noted as having some redundancy with rods/cones.

Source

Circadian Rhythm Sleep Disorders: Part I, Basic Principles, Shift Work and Jet Lag Disorders

Robert L. Sack et al. · SLEEP · 2007

DOI 10.1093/sleep/30.11.1460

narrative_reviewCited 643×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →