Living by the clock: the circadian pacemaker in older people

Research output: Contribution to journal/periodicalArticleScientificpeer-review


The suprachiasmatic nucleus (SCN) of the hypothalamus is considered to be a critical component of a neural oscillator system implicated in the timing of a wide variety of biological processes. The circadian cycles established by this biological clock occur throughout nature and have a period of approximately 24 h. With advancing age, however, these daily fluctuations deteriorate, leading to disrupted cycles with a reduced amplitude. In humans, age-related changes have been described for hormonal rhythms, body core temperature, sleep-wakefulness and several other behavioral cycles. It appears that the disruption of circadian rhythms and the increased incidence of disturbed sleep during aging are paralleled by age-related alterations in the neural and temporal organization of the SCN and a decreased photic input to the clock. The many lines of evidence of age-related decrements in circadian time-keeping and the observed neuronal degeneration of the SCN in senescence strongly suggest that the circadian pacemaker in the human brain becomes progressively disturbed during aging.

Original languageEnglish
Pages (from-to)33-51
Number of pages19
JournalAgeing Research Reviews
Issue number1
Publication statusPublished - Feb 2006


  • Aging/genetics
  • Circadian Rhythm/genetics
  • Humans
  • Suprachiasmatic Nucleus/anatomy & histology


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