Circadian rhythms and depression: Effects of exercise in an animal model

Leah C. Solberg*, Teresa H. Horton, Fred W. Turek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


There is a clear link between altered circadian rhythms and depressive disorders, although the nature of this relationship is unknown. In addition, exercise affects both mood and alters clock function. To investigate the relationship between circadian rhythms, depression, and exercise, 3-wk-old mice housed on a 12:12-h light-dark cycle were exposed to chronic stress (CS) for 6 wk before being placed into constant darkness (DD). One-half of both the control and stressed mice were given access to a running wheel. Stressed mice consumed significantly less of a 2% sucrose solution during CS and exhibited a significant increase in immobility in the forced swim test 3 wk after the termination of stress relative to control mice. These effects were more pronounced in mice without running wheels. Stressed mice also exhibited altered percent distribution of total activity and increased fragmentation of daily activity rhythms during CS relative to control mice. Alterations in percent distribution were more pronounced in animals without running wheels. No activity rhythm changes were seen in DD, and there were no differences in light-induced phase shifts between stressed and control mice. These results suggest that CS causes long-term depressive-like symptoms but does not have long-lasting effects on activity rhythms. These changes were more pronounced in mice without running wheels, suggesting that exercise may protect against the harmful effects of stress.

Original languageEnglish (US)
Pages (from-to)R152-R161
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number1 45-1
StatePublished - Jan 1999


  • Anhedonia
  • C57BL/6J mice
  • Chronic stress
  • Forced swim test

ASJC Scopus subject areas

  • Physiology (medical)
  • Physiology


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