Normal human subjects with slow reaction times and larger time estimations after waking have diminished delta sleep

A sample of 42 healthy young male human subjects was submitted to whole night polysomnography and attention performance tests upon awakening (simple visuomotor reaction time, RT, and time estimation, TE). In order to test whether performance is related to specific sleep parameters, the 15 fastest subjects (mean = 210 msec) and 15 slowest subjects (mean = 357 msec) in RT were compared in their TE and sleep parameters. Fast subjects were more precise in the estimation of 10 sec intervals (9.89; S.E. = 0.23 sec) than slow subjects (10.73; S.E. = 0.32). Slow subjects had significantly less delta sleep (mean = 73 min) than fast subjects (100 min, P less than 0.01) and otherwise similar sleep parameters. It can be suggested that attention after awakening is related to the amount of delta sleep in the night.