title: Circadian behavioral rhythms during various light-intensity cycles in rats.
abstract: Sleep, ambulation and drinking were recorded on 5 kinds of light-intensity cycles fluctuating between 300 lux and 0 lux with a 24-hr period in rats. The waveforms of the cycles were rectangular wave (RA), sinusoidal wave (SO), triangular wave (TA), descending saw-tooth wave (ST-d) and ascending saw-tooth wave (ST-a). Each condition was maintained for 28 days. Thereafter, the rats were released into constant darkness (DD) for 20 days. The circadian behavioral rhythms clearly entrained to RA, SO, TA and ST-a, but not to ST-d. The waveforms of the behavioral rhythms varied depending on those of the fluctuating light-intensity cycles, and were quite different from those in RA and DD. Daily amounts of slow wave sleep and paradoxical sleep were hardly affected by the lighting conditions, while those of ambulation and drinking were decreased on the other light-intensity cycles than RA. These results present new aspects of entrainment and masking of circadian rhythm by light.
authors.affiliation: Department of Psychology, Tokyo Metropolitan Institute for Neurosciences, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Usui
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Honda
authors.forename: S
authors.initials: S
authors.lastname: Ebihara
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology*; D004327:Drinking Behavior / Q000502:physiology*; D008029:Lighting; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010507:Periodicity; D051381:Rats; D011919:Rats, Inbred Strains; D012890:Sleep / Q000502:physiology*