Binocular and monocular/unihemispheric sleep in the domestic chick (Gallus gallus) after a moderate sleep deprivation.

Binocular (Bin-sleep) and monocular/unihemispheric sleep (Mo-Un sleep) were studied in domestic chicks (Gallus gallus) after an 8 h period of sleep deprivation. Eleven-day-old chicks were divided into three groups: two non-deprived (N-DEP1 and N-DEP2) and one deprived for 8 h (DEP-8H). Deprivation was performed by placing chicks on a treadmill on which they were forced to walk continuously. Sleep behaviour was recorded for 6 h consecutively immediately after the end of sleep deprivation. During the recovery period, sleep-deprived chicks slept for a longer duration, spent significantly more time in binocular sleep and slept for significantly longer episodes that did control chicks. Regarding Mo-Un sleep, sleep deprivation seems to affect the right hemisphere by reducing the number of episodes and the time spent sleeping with the left eye closed. These results suggest that sleep-deprivation significantly influences the pattern of sleep in domestic chicks allowing for a better recovery.