The nocturnal suppression of aqueous humor flow in humans is not blocked by bright light

Normal human subjects were studied hourly by fluorophotometry to measure the normal circadian rhythm of aqueous humor flow. On a separate day, the subjects slept for approximately 1 hr after lunch; this short nap was not found to have any effect on aqueous flow. On a separate night, the subjects slept under a bright light of 2500 lux; the light was not found to have any effect on flow in the sleeping subjects. Because bright light blocks melatonin release in humans, nocturnal suppression of aqueous flow in humans may not be driven by systemic melatonin release.