scholarly journals Enhancement and Suppression of Ultradian and Circadian Rhythms across the Female Hamster Reproductive Cycle

2012 ◽  
Vol 27 (3) ◽  
pp. 246-256 ◽  
Author(s):  
Brian J. Prendergast ◽  
Annaliese K. Beery ◽  
Matthew J. Paul ◽  
Irving Zucker
Keyword(s):  
Circadian Rhythms ◽  
Reproductive Cycle ◽  
Female Hamster

Suprachiasmatic nuclei influence circannual and circadian rhythms of ground squirrels

1983 ◽  
Vol 244 (4) ◽  
pp. R472-R480 ◽  
Author(s):  
I. Zucker ◽  
M. Boshes ◽  
J. Dark
Keyword(s):  
Body Weight ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Reproductive Cycle ◽  
Ground Squirrels ◽  
Circadian Activity ◽  
Suprachiasmatic Nuclei ◽  
Medial Basal Hypothalamus ◽  
Circadian Organization ◽  
Activity Cycles

Golden-mantled ground squirrels, maintained under constant conditions of photoperiod and temperature sustained lesions of the suprachiasmatic nuclei (SCN) or of the medial basal hypothalamus. Destruction of the SCN eliminated or disrupted circadian activity rhythms and shortened the period of the circannual reproductive cycle. Circannual body weight cycles were eliminated or disrupted in several SCN-lesioned animals and one squirrel had a 3- to 5-mo body weight rhythm; however, most SCN-lesioned squirrels with disrupted circadian activity cycles manifested normal circannual body weight rhythms. The SCN are important for circadian organization of locomotor activity of this diurnal rodent, but the generation and expression of circannual body weight and reproductive rhythms can proceed in the absence of coherent circadian organization. The SCN are less essential for the generation and expression of circannual than of circadian cycles

The Biological Clock and Sleep in the Elderly

2006 ◽  
Vol 19 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Myriam Juda ◽  
Mirjam Münch ◽  
Anna Wirz-Justice ◽  
Martha Merrow ◽  
Till Roenneberg
Keyword(s):  
Circadian Rhythms ◽  
Biological Clock ◽  
The Elderly ◽  
Early Morning ◽  
Behavioral Changes ◽  
Older Age ◽  
Age Related ◽  
Theoretical Considerations ◽  
Sleep Difficulties ◽  
Circadian Biology

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.

Circadian Rhythms: A Tutorial

1982 ◽  
Vol 27 (12) ◽  
pp. 931-932
Author(s):  
Gerald S. Wasserman
Keyword(s):  
Circadian Rhythms
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