Long-term trends in human eye blink rate.

Long-term recordings of normal human eye blink behavior (up to 14 h continuously) showed a number of periodic trends in blink rate. Mean rates varied from 2 to 50 blinks/min and periods ranged from 10 min to 2.5 h. Three dominant groupings of mean rates were observed (1) under 6, (2) 8--15 and (3) 20--30 blinks/min; these groups appear to be related to more or less distinct behavioral states of the individual. Blink amplitudes also varied and amplitude and rate showed correlations of possible functional significance. Vision-related behaviors affect both the mean rate of blinking and blink amplitude, and may impose a characteristic strategy on the timing of the individual blinks as well. The latter is referred to as bimodal blinking; this strategy contrasts with the random occurrence of blinks seen normally.