title: Sleep patterns during rearing under different environmental conditions in juvenile rats.
abstract: Male Wistar rats were chronically implanted at weaning with electrodes for recording EEG amd EMG. From one month of age, they were randomly assigned to either 24 h or 2 h daily 'enriched' (EC), 'standard' (SC) or 'isolated' (IC) rearing conditions. The 24 h-EC group showed the following changes with respect to both the SC and the IC groups: (a) more quiet sleep time; (b) more active sleep time, and (c) shorter active sleep latency. These differences were evident by the third week of environmental conditioning, became statistically significant by 4 weeks, and continued to increase throughout the rest of the enrichment period. None of the sleep parameters showed any significant differences between the SC and the IC groups. The 2 h-EC rats showed an increase in both quiet sleep and active sleep time during the experimental period, whereas the controls showed the expected decline. Morphological investigations at 3 months of age revealed a significant weight increase in the cerebral cortex, and even more so in the hypothalamus as compared with the control group in the 2 h-EC rats.
mesh_terms: D000375:Aging; D000818:Animals; D001921:Brain / Q000378:metabolism; D002540:Cerebral Cortex / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012894:Sleep Stages / Q000502:physiology*; D012931:Social Environment; D012934:Social Isolation
chemical_list: D004247:DNA