Alcohol consumption before sleep negatively affects next-day performance

Key takeaways:

• Drinking alcohol before sleep significantly slowed reaction times up to 4 hours after waking.
• Even with adequate sleep, reaction times still suffered after 3 consecutive nights of drinking.

INDIANAPOLIS — Results of a study presented here demonstrated that alcohol consumed within 1 hour of bedtime had a negative effect on psychomotor vigilance performance the next day.

Mary A. Carskadon, PhD, professor of psychiatry and human behavior at Alpert Medical School of Brown University, and colleagues conducted an analysis of 26 adults with a mean age of 31 years to determine whether consuming alcohol prior to sleep impacts psychomotor vigilance performance up to 3 days later.

All participants slept at home for 7 to 12 days, with a sleep duration of 8 to 9 hours, then underwent two 3-night in-lab polysomnography sessions at least 3 days apart. Alcohol plus a mixer and mixer only (control) were given via three drinks over a period of 45 minutes. Drinking ended 1 hour prior to bedtime and the target alcohol intake was .08g%.

Researchers administered the psychomotor vigilance (PVT, Ambulatory Monitoring Inc.) performance battery in the lab 1.5 hours prior to drinking to serve as baseline, then again in the morning after sleep and a light breakfast (50 minutes after waking). Participants then took the battery home with instructions on when to take the test: 3 to 4.5 hours after waking and again in the afternoon, about 7.5 to 9 hours after waking. Lapses, median reaction time, reciprocal reaction time and mean reaction time of fastest 10% of reaction times were analyzed.

According to Carskadon, every PVT variable showed a main effect of alcohol that was “very clear and very consistent.” There was a statistically significant difference between mixer and alcohol for lapses, with day-1 lapses meaningfully more frequent in the alcohol condition vs. the mixer, according to Carskadon. The same was true on day 2 but not day 3.

Additionally, meaningful differences were noted in the first (morning lab) and second (mid-morning home) tests, but not the third (afternoon home test).

Median reaction time was about 10 milliseconds slower in the alcohol condition vs. the mixer, with differences on the second and third days. Slower reaction time persisted in the morning lab (P = .008) and mid-morning home tests (P < .001), but there was no difference in the afternoon home test.

Similarly, alcohol had a statistically significant main effect on reciprocal reaction time, with the difference increasing on the second and third days, with slower timing in the morning in-lab and mid-morning home testing timeframes.

Lastly, fastest 10% was also negatively affected by alcohol use the night before, with no effect until the second day that was maintained on day 3, and morning in-lab (P = .003) and mid-morning home (P = .001) and afternoon home (P = .068 [trend]) tests showing differences, but not the pre-drinking lab test.

“Pre-sleep alcohol had a significant negative effect on all PVT variables,” Carskadon concluded. “Some effects were apparent up to 7 hours after waking and most continued for all 3 days.”