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Sex differences within sleep in gonadally intact rats
Kevin M Swift1, Karina Keus2, Christy Gonzalez Echeverria3
1Molecular and Integrative Physiology Department, University of Michigan, Ann Arbor, MI.
Sleep
|December 1, 2019
Summary
The female estrous cycle significantly alters sleep patterns in rodents, with hormonal shifts during proestrus reducing sleep and increasing wakefulness, followed by a rebound effect during estrus. These cycle-dependent sleep changes impact brain activity and may affect physiological processes.
Area of Science:
- Neuroscience
- Reproductive Biology
- Sleep Science
Background:
- Sleep is crucial for physiological and neural functions.
- The menstrual cycle influences sleep in humans, but estrous cycle effects on rodent sleep are understudied.
- This knowledge gap limits understanding of female-specific disease mechanisms.
Purpose of the Study:
- To investigate the impact of the estrous cycle on sleep architecture and brain activity in female rodents.
- To compare sleep patterns between females across the estrous cycle and males.
Main Methods:
- Electroencephalographic (EEG) recordings from multiple brain regions were used to analyze sleep states, spectral power, and interregional coherence.
- Sleep traits were assessed in freely cycling female rodents throughout their estrous cycle and compared to males.
Main Results:
- Proestrus (high hormone phase) was associated with decreased non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, and increased wakefulness compared to other phases and males.
- A subsequent sleep rebound occurred during estrus, with increased NREM and REM sleep.
- Specific spectral power increases (delta, gamma during NREM; theta during REM) and enhanced interregional coherence were observed during proestrus and estrus.
Conclusions:
- The estrous cycle significantly influences multiple aspects of sleep in female rodents, beyond previously recognized effects.
- Hormonal fluctuations during the estrous cycle induce distinct sleep-wake patterns and brain activity.
- These findings highlight sex differences in sleep regulation tied to the estrous cycle, with potential implications for physiological processes and disease research.
