Light effects on circadian timing system of a diurnal primate, the squirrel monkey

1985 ◽  
Vol 249 (2) ◽  
pp. R274-R280 ◽  
Author(s):  
T. M. Hoban ◽  
F. M. Sulzman
Keyword(s):  
Squirrel Monkey ◽  
Response Curve ◽  
Phase Response Curve ◽  
Phase Response ◽  
Day Length ◽  
Circadian Timing ◽  
Subjective Night ◽  
Timing System ◽  
Circadian Timing System ◽  
Light Effects

We examined light effects on the circadian timing system of the squirrel monkey. A phase-response curve to 1-h pulses of light was constructed for the drinking rhythm of six animals. The phase-response curve was the same type as that exhibited by nocturnal rodents, with phase delays occurring early in the subjective night and phase advances late in the subjective night. The range of entrainment of 10 monkeys to days with 1 h light and x h dark was determined. Five monkeys used to generate the phase-response curve were also used in the range of entrainment determination. For short light-dark cycles the range of entrainment was smaller than that expected, with no monkey entraining to a day length of less than 23.5 h.

scholarly journals Photic phase response curve in Octodon degus: assessment as a function of activity phase preference

2000 ◽  
Vol 278 (5) ◽  
pp. R1385-R1389 ◽  
Author(s):  
Martien J. H. Kas ◽  
Dale M. Edgar
Keyword(s):  
Circadian Rhythms ◽  
Response Curve ◽  
Phase Response Curve ◽  
Activity Level ◽  
Phase Response ◽  
Octodon Degus ◽  
Photic Entrainment ◽  
Activity Phase ◽  
Subjective Night ◽  
Phase Preference

Light exposure during the early and late subjective night generally phase delays and advances circadian rhythms, respectively. However, this generality was recently questioned in a photic entrainment study in Octodon degus. Because degus can invert their activity phase preference from diurnal to nocturnal as a function of activity level, assessment of phase preference is critical for computations of phase reference [circadian time (CT) 0] toward the development of a photic phase response curve. After determining activity phase preference in a 24-h light-dark cycle (LD 12:12), degus were released in constant darkness. In this study, diurnal ( n = 5) and nocturnal ( n = 7) degus were randomly subjected to 1-h light pulses (30–35 lx) at many circadian phases (CT 1–6: n= 7; CT 7–12: n = 8; CT 13–18: n = 8; and CT 19–24: n = 7). The circadian phase of body temperature (Tb) onset was defined as CT 12 in nocturnal animals. In diurnal animals, CT 0 was determined as Tb onset + 1 h. Light phase delayed and advanced circadian rhythms when delivered during the early (CT 13–16) and late (CT 20–23) subjective night, respectively. No significant phase shifts were observed during the middle of the subjective day (CT 3–10). Thus, regardless of activity phase preference, photic entrainment of the circadian pacemaker in Octodon degus is similar to most other diurnal and nocturnal species, suggesting that entrainment mechanisms do not determine overt diurnal and nocturnal behavior.

Role of the suprachiasmatic nuclei in the circadian timing system of the squirrel monkey. I. The generation of rhythmicity

1984 ◽  
Vol 300 (2) ◽  
pp. 275-284 ◽  
Author(s):  
H. Elliott Albers ◽  
Ralph Lydic ◽  
Philippa H. Gander ◽  
Martin C. Moore-Ede
Keyword(s):  
Squirrel Monkey ◽  
Suprachiasmatic Nuclei ◽  
Circadian Timing ◽  
Timing System ◽  
Circadian Timing System

Synchronization of two coupled pacemaker cells based on the phase response curve

2009 ◽  
Vol 4 (1) ◽  
pp. 57-66
Author(s):  
Hossein Gholizade-Narm ◽  
Asad Azemi ◽  
Morteza Khademi ◽  
Masoud Karimi-Ghartemani
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Phase Response ◽  
Pacemaker Cells

scholarly journals Metabolic disturbances: role of the circadian timing system and sleep

2016 ◽  
Vol 8 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Navin Adhikary ◽  
Santosh Lal Shrestha ◽  
Jia Zhong Sun
Keyword(s):  
Metabolic Disturbances ◽  
Circadian Timing ◽  
Timing System ◽  
Circadian Timing System

scholarly journals The challenges of adolescent sleep

2020 ◽  
Vol 10 (3) ◽  
pp. 20190080 ◽  
Author(s):  
Gaby Illingworth
Keyword(s):  
Developmental Period ◽  
Sleep Health ◽  
Insufficient Sleep ◽  
Cognitive Health ◽  
Circadian Timing ◽  
Timing System ◽  
Adolescent Sleep ◽  
Circadian Timing System ◽  
Exogenous Factors ◽  
Adolescent Functioning

Sleep is vital for our physical, emotional and cognitive health. However, adolescents face many challenges where their sleep is concerned. This is reflected in their sleep patterns including the timing of their sleep and how much sleep they achieve on a regular basis: their sleep is characteristically delayed and short. Notably, insufficient sleep is associated with impairments in adolescent functioning. Endogenous and exogenous factors are known to affect sleep at this age. Alterations in the bioregulation of sleep, comprising the circadian timing system and the sleep/wake homeostatic system, represent the intrinsic mechanisms at work. Compounding this, environmental, psychosocial and lifestyle factors may contribute to shortened sleep. This review discusses the amount of sleep gained by adolescents and its implications, the challenges to adolescent sleep and the interventions introduced in an effort to prioritize sleep health in this important developmental period.

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