Late-afternoon ethanol intake affects nocturnal sleep and the sleep EEG in middle-aged men.
Level 3 - non-randomized controlled study
Controlled clinical trial without explicit mention of randomization in the abstract
PubMed 8959467 · doi:10.1097/00004714-199612000-00004
What was done
Ten healthy middle-aged men (mean age: 61.6 ± 0.9 years) received a moderate dose of ethanol (0.55 g/kg of body weight) or a mineral water control condition administered 6 hours prior to bedtime. Breath-ethanol concentrations reached zero in all subjects before the sleep episode began. Sleep efficiency, total sleep time, sleep stages, subjective sleep perception, and sleep electroencephalogram (EEG) spectral power density were measured.
What was found
Compared with the control condition, sleep was perceived as more superficial. Sleep efficiency, total sleep time, stage 1 sleep, and rapid eye movement (REM) sleep were reduced. Wakefulness in the second half of the sleep episode showed a twofold increase. In non-REM sleep (1.25-2.5 Hz) and REM sleep (1.25-1.5 Hz), EEG power density in low delta frequencies was enhanced. In slow-wave sleep, power density was increased in low-frequency bands (1.25-1.5, 2.25-4.0, 4.75-5.0 Hz), the alpha band (8.25-9.0 Hz), and the sigma band (12.25-13.0 Hz). Absolute baseline and intervention values for sleep stages were not reported in the abstract.
Why it matters
This study demonstrates that moderate alcohol consumption as early as late afternoon disrupts sleep consolidation and alters sleep EEG architecture, even after ethanol is fully cleared from breath before bedtime.
Limits
The sample size is very small (n = 10) and limited exclusively to healthy middle-aged men. The abstract omits exact numerical values for sleep duration and stage distributions, and does not specify whether the crossover sequence was randomized or blinded.
Cited by
- supports Consuming alcohol in the afternoon can still cause lingering disruptions to sleep efficiency, total sleep time, stage 1 sleep, REM sleep, and nighttime wakefulness even when breath or blood alcohol is zero at bedtime.