Now a study demonstrates that late-night alcohol might decrease the amount of necessary overnight repair work that the body can do.
Subjects in the study drank strong, weak or alcohol-free beverages an hour-and-40-minutes before going to bed. The more booze the volunteers imbibed, the higher their overnight heart rate. These rapid beats were an indication that their bodies were not in the most productive rest mode, say the researchers. The work appears in the journal Alcoholism: Clinical & Experimental Research. [Yohei Sagawa et al., "Alcohol Has a Dose-Related Effect on Parasympathetic Nerve Activity During Sleep"]
The findings might help explain why those who frequently drink often suffer from insomnia at night and sleepiness during the day, as well as more long-term health effects.
So if you're looking for better, more healthful sleep, maybe avoid the night-time nightcap.
For those interested, here is the study abstract:
Alcohol Has a Dose-Related Effect on Parasympathetic Nerve Activity During Sleep
- Yohei Sagawa,
- Hideaki Kondo,
- Namiko Matsubuchi,
- Takaubu Takemura,
- Hironobu Kanayama,
- Yoshihiko Kaneko,
- Takashi Kanbayashi,
- Yasuo Hishikawa,
- Tetsuo Shimizu
- Autonomic Nerve Activity;
- Heart Rate Variability
Methods: Ten healthy male university students were enrolled in this study. An alcoholic beverage was given to each subject at a dosage of 0 (control), 0.5 (low dose: LD), or 1.0 g (high dose: HD) of pure ethanol/kg of body weight. All experiments were performed at 3-week intervals. On the day of the experiment, a Holter electrocardiogram was attached to the subject for a 24-hour period, and the subject was instructed to drink the above-described dosage of alcoholic beverage 100 minutes before going to bed; polysomnography was then performed for 8 hours. Power spectral analysis of the HRV was performed using the maximum entropy method, and the low- (LF: 0.04 to 0.15 Hz) and high-frequency (HF: 0.15 to 0.4 Hz) components along with LF/HF ratio were calculated.
Results: As alcohol consumption increased, the heart rate increased and the spectral power of HRV measured at each frequency range decreased. Higher doses of ethanol also increased the LF/HF ratio compared with the measured ratio of the control group.
Conclusions: Acute ethanol intake inhibits parasympathetic nerve activity and results in predominance of sympathetic nerve activity during sleep, in a dosage-dependent manner. The results of this study suggest that ethanol interferes with the restorative functions of sleep