title: Monocular sleep in male domestic chicks.
abstract: Behavioural sleep during the first 2 weeks after hatching was studied in male chicks reared with an imprinting object (I-chicks) and in social isolation (NI-chicks). Time spent in sleeping with both eyes closed (binocular sleep) decreased gradually with age in both I-chicks and in NI-chicks whilst the number of episodes of binocular sleep decreased with age in NI-chicks but not in I-chicks. The pattern of monocular sleep (only one eye closed) of both I-chicks and NI-chicks showed no significant bias towards predominant left- or right-eye closure during the first week. During the second week, I-chicks showed a tendency towards more pronounced left-eye closure with a peak on day 10, whilst NI-chicks showed a tendency for more pronounced right-eye closure with peaks on days 9 and 11. In a different group of chicks, changing the colour of the imprinting object on day 8 produced a shift towards right-eye closure. In contrast, the removal of the imprinting object on day 8 did not cause any change in the pattern of monocular sleep. Differences with respect to sleeping patterns previously observed in females chicks are discussed.
authors.affiliation: Dipartimento di Psicologia Generale, Università di Padova, Via Venezia 8, 35131 Padova, Italy. giangastone.mascetti@unipd.it
authors.forename: Gian Gastone
authors.initials: GG
authors.lastname: Mascetti
authors.forename: Daniela
authors.initials: D
authors.lastname: Bobbo
authors.forename: Marina
authors.initials: M
authors.lastname: Rugger
authors.forename: Giorgio
authors.initials: G
authors.lastname: Vallortigara
mesh_terms: D000367:Age Factors; D000818:Animals; D001245:Association Learning; D002645:Chickens; D003118:Color Perception; D007839:Functional Laterality; D007173:Imprinting, Psychological; D009769:Object Attachment; D012890:Sleep; D012934:Social Isolation; D015349:Vision, Monocular