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Changes in diaphragmatic EMG activity during sleep in space
Y Takasaki1, K Kamio, M Okamoto
1Second Department of Internal Medicine, School of Medicine, Tokai University, Kanagawa, Japan.
The American Review of Respiratory Disease
|September 1, 1993
Summary
Gravity significantly impacts upper airway resistance during sleep. Reduced gravity in space lessened the breathing effort during non-REM sleep, suggesting gravity
Area of Science:
- Space physiology
- Respiratory control
- Sleep science
Background:
- Increased upper airway resistance (UAR) during sleep is a common issue.
- The role of gravity in UAR during sleep remains largely unknown.
- Understanding gravity's influence is crucial for spaceflight and terrestrial health.
Purpose of the Study:
- To quantitatively evaluate the gravitational influence on diaphragmatic EMG activity (EMGdi).
- To estimate the effect of UAR in space by measuring EMGdi in an astronaut.
- To compare breathing effort during wakefulness and sleep under different gravitational conditions.
Main Methods:
- Diaphragmatic EMG activity (EMGdi) was recorded using surface electrodes.
- Recordings were made on Earth (control) and during a short-term space mission (space).
- EMGdi during quiet breathing in wakefulness was normalized to 100% for comparison.
Main Results:
- On Earth, EMGdi was significantly higher during all sleep stages (non-REM and REM) compared to wakefulness.
- In space, EMGdi showed no significant difference between wakefulness and non-REM sleep stages.
- In space, EMGdi during REM sleep was significantly higher than during wakefulness and non-REM sleep.
Conclusions:
- Gravity plays a significant role in increasing upper airway resistance during sleep in healthy humans.
- Reduced gravitational load in space diminishes the increase in breathing effort during non-REM sleep.
- These findings suggest gravity's influence on UAR may be more substantial than previously thought, potentially outweighing muscle atonia effects.