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Updated: May 31, 2026
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Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Published on: August 8, 2019
Age-related decline in circadian output
Takahiro J Nakamura1, Wataru Nakamura, Shin Yamazaki
1Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, California 90024-1759, USA.
Summary
Aging degrades the brain's central circadian clock (suprachiasmatic nucleus) in mice, reducing neural activity rhythms before molecular clock disruption. This impacts sleep/wake cycles in older mammals.
Area of Science:
- Neuroscience
- Chronobiology
- Aging Research
Background:
- Sleep/wake cycle disruptions, including reduced rhythm amplitude and fragmented sleep, are common in aging mammals.
- An age-related decline in the suprachiasmatic nucleus (SCN), the central circadian clock, is a potential cause.
Purpose of the Study:
- To investigate age-related changes in SCN neural activity and its molecular clockwork.
- To determine if neural output degradation precedes molecular clock deficits in aging.
Main Methods:
- In vivo multiunit neural activity (MUA) recordings from the SCN of young and middle-aged mice.
- Analysis of neural activity rhythms in the SCN and subparaventricular zone.
- Assessment of PER2 protein expression in the SCN.
Main Results:
- A significant reduction in the amplitude of day-night differences in SCN MUA was observed in middle-aged mice compared to young mice.
- Neural activity rhythms were degraded in the subparaventricular zone of older mice.
- PER2 expression in the SCN showed only minor deficits in middle-aged mice, indicating molecular clock integrity.
Conclusions:
- Aging degrades circadian output at the level of SCN neural activity rhythms.
- This decline in neural rhythm amplitude occurs before significant disruption of the SCN molecular clockwork.
- Age-related changes in SCN neural function may underlie sleep/wake cycle disturbances in aging.
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