Sleep characteristics in the turkey Meleagris gallopavo.

Electrophysiological and behavioral characteristics of the states of vigilance were analyzed in chronically implanted specimens of the turkey Meleagris gallopavo (M. gallopavo). Five different states of vigilance were observed throughout the nyctohemeral period: active wakefulness (AW), quiet wakefulness (QW), drowsiness (D), slow wave sleep (SWS) and rapid eye movement (REM) sleep. These states exhibit characteristics similar to those described in other bird species. Sleep periods displayed a polyphasic distribution; however, they showed the tendency to concentrate between 2100 and 0900 h in spite of the fact that the recordings were carried out under constant illumination. Sleep period occupied 45.71% of the nyctohemeral cycle, 43.33% corresponded to SWS, while 2.38% to REM sleep. The average duration of the REM sleep phase was very short, lasting 7.7+/-0.55 s (mean+/-S.D.). In contrast, its frequency was very high with an average recurrence of 268+/-63 phases throughout the nyctohemeral cycle. The short duration of REM sleep phase presented by the turkey as by other bird species studied up to now may be dependent upon genetic factors shared by this group of vertebrates.