Aqueous humor flow during sleep.

The rate of aqueous humor flow of 19 normal subjects was measured by a fluorescein clearance technique during the day, during sleep (at night) and during sleep deprivation (at night). Subjects engaged in routine activities during the daytime measurements and slept in comfortable quarters during the nighttime measurement. They remained awake and active during the sleep deprivation study. The nomographic method of Coakes and Brubaker , a method in which the subject is not disturbed at all during the critical 5-hr period, was used to calculate flow. Flow was lower during sleep in all but one subject. The range of nighttime flow suppression was 8% to 68% in all of the other subjects with a mean suppression of 45% +/- 20%. Aqueous flow was lower at night even when the subjects were awake but was lowest during sleep at night. The reduction of aqueous flow during sleep is comparable with the suppression that can be achieved with carbonic anhydrase inhibitors or beta adrenergic blockers.