scholarly journals Precision of entrained circadian activity rhythms under natural photoperiodic conditions

1972 ◽  
Vol 59 (6) ◽  
pp. 276-277 ◽  
Author(s):  
J. Aschoff ◽  
S. Daan ◽  
J. Figala ◽  
K. M�ller
Keyword(s):  
Circadian Activity ◽  
Activity Rhythms

753 The role of circadian activity rhythms in depressive symptoms among female nursing students

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A293-A294
Author(s):  
Xin Zhang ◽  
Shih-Yu Lee
Keyword(s):  
Nursing Education ◽  
Depressive Symptoms ◽  
Nursing Students ◽  
Conceptual Model ◽  
Depression Scale ◽  
Psychological Problems ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Wrist Actigraphy ◽  
Insomnia Symptoms

Abstract Introduction Depression is prevalent among nursing students. Rumination and sleep-wake rhythms are associated to mental illness; however, no clear path has been found. This exploratory study aimed to examine the associations among circadian activity rhythms (CAR), rumination, and depressive symptoms in female nursing students; further, to test a hypothesized CAR conceptual model. Methods A total of 148 female nursing junior students in China completed a battery of questionnaires, including Athens Insomnia Scale (AIS), Ruminative Responses Scale (RRS), and Self-rating Depression Scale (SDS). Wrist actigraphy was used to collect total sleep time, CAR, and acrophase (time of the peak of the fitted activity curve). The path analysis was explored by using SPSS and AMOS. Results The mean age of the students was 20.64 years (SD = 0.86). About 58.8% of the participants were either mild or moderate depressed. About 93.9% of the students reported significant insomnia symptoms (AIS scores >6). Rumination was measured by the RRS (M= 2.01, SD = 0.54), and students scored higher in brooding than that of reflective pondering (2.07 vs. 1.95). The average of TST was 394.59 minutes (SD = 51.92). The CAR ranged from 0.40 to 0.98, with a mean of 0.75 (SD = 0.11). The acrophase ranged from 12:46 to 20:14 (median 16:30), with a later acrophase indicates of a more delayed circadian phase. The final model shows satisfactory fit (χ2= 2.238, p= .327); a better CAR can indirectly reduce depressive symptoms by directly reducing brooding (B = -1.149) and improving insomnia symptoms (B = -6.6443). Conclusion In order to prevent psychological problems of nursing students, ruminating and CAR should be part of health screening. The novel conceptual model provides a basis for reforming nursing education to prevent psychological problems. Support (if any) Chinese National Natural Science Foundation [71603279]

Effects of Pregnancy and Parturition on Free-Running Circadian Activity Rhythms in the Rat

1987 ◽  
Vol 4 (2) ◽  
pp. 183-187 ◽  
Author(s):  
Alan M. Rosenwasser ◽  
Susanne J. Hollander ◽  
Norman T. Adler
Keyword(s):  
Circadian Activity ◽  
Activity Rhythms ◽  
Free Running

Opioid induced non-photic phase shifts of hamster circadian activity rhythms

2000 ◽  
Vol 873 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Mirnela Byku ◽  
Robert L Gannon
Keyword(s):  
Phase Shifts ◽  
Circadian Activity ◽  
Activity Rhythms

Photic Response Parameters of Circadian Rhythms in The Spinifex Hopping Mouse, Notomys alexis.

1996 ◽  
Vol 19 (1) ◽  
pp. 11
Author(s):  
A.J.P. Francis ◽  
G.J. Coleman
Keyword(s):  
Circadian Rhythms ◽  
Phase Relations ◽  
Constant Light ◽  
Constant Darkness ◽  
Biological Clocks ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Controlled Conditions ◽  
Australian Native Rodent ◽  
Photic Response

Circadian rhythms are generated endogenously by biological clocks or 'pacemakers', which are responsive to significant environmental stimuli termed zeitgebers. Interactions between pacemakers and zeitgebers provide the basis for synchronisation by light-dark (LD) cycles, and the characteristics of each of these elements determines the phase-relations maintained between an animal's circadian activity rhythms and the natural temporal environment. We report here the basic photic response parameters for an Australian native rodent, Notomys alexis. Under controlled conditions of constant darkness or constant light, N. alexis were found to 'free-run', and with periods different from 24 hours. Under LD cycles N. alexis were strictly nocturnal although, compared to other rodents, entrainment to LD cycles was relatively unstable. This may indicate that N. alexis are not strongly dependent on the LD cycle as a zeitgeber.

Entrainment of Syrian hamster circadian activity rhythms by neonatal melatonin injections

1996 ◽  
Vol 270 (3) ◽  
pp. R533-R540 ◽  
Author(s):  
J. Grosse ◽  
A. Velickovic ◽  
F. C. Davis
Keyword(s):  
Circadian Rhythms ◽  
Suprachiasmatic Nucleus ◽  
Syrian Hamster ◽  
Circadian Activity ◽  
Syrian Hamsters ◽  
Activity Rhythms ◽  
Vehicle Injection ◽  
Two Phases ◽  
Melatonin Injection

The circadian rhythms of fetal and neonatal rodents are entrained by their mother. This entrainment is dependent upon the maternal suprachiasmatic nucleus (SCN), but the mechanism of entrainment is unknown. Administration of the pineal hormone melatonin to pregnant, SCN-lesioned female Syrian hamsters entrains the activity rhythms of their hamster pups. The aim of this study was to determine whether melatonin injected directly in neonatal Syrian hamsters is able to entrain circadian rhythms and, if so, for how long this effect persists during development. Injection of melatonin in two groups of hamster pups at opposite phases on postnatal days 1-5 entrained the onset of activity rhythms on the day of weaning to two phases 10.67 h apart. Melatonin injection did not entrain activity rhythms to opposite phases on either postnatal days 6-10 or 21-25. Vehicle injection did not entrain animals to opposite phases at any of the ages studied. These results demonstrate that melatonin is able to act directly on the neonate to cause entrainment and that this effect disappears after postnatal day 6.

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