The effect of caffeine on subsequent sleep: A systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of 24 studies on caffeine intake and sleep parameters.
PubMed 36870101 · doi:10.1016/j.smrv.2023.101764
What was done
A systematic review and meta-analysis of 24 studies was conducted to evaluate the effects of caffeine on night-time sleep parameters and to model the minimum time prior to bedtime that caffeine should be avoided to prevent sleep loss.
What was found
Caffeine consumption reduced total sleep time by 45 min and sleep efficiency by 7%, increased sleep onset latency by 9 min, and increased wake after sleep onset by 12 min. For sleep architecture, light sleep (N1) duration increased by 6.1 min (+1.7% proportion) and deep sleep (N3 and N4) duration decreased by 11.4 min (-1.4% proportion). To prevent reductions in total sleep time, the calculated cut-off window was at least 8.8 h prior to bedtime for a standard coffee (107 mg in 250 mL) and at least 13.2 h prior to bedtime for a pre-workout supplement (217.5 mg).
Why it matters
This review establishes specific quantitative cut-off windows for caffeine consumption before sleep and measures the exact degree of sleep architecture disruption caused by caffeine intake.
Limits
The abstract does not report participant characteristics (such as age, habitual caffeine tolerance, or sex), total sample size across the 24 studies, study designs included, or confidence intervals and variance for the reported effect sizes.
Cited by
- supports Drinking caffeine within 8 to 10 hours before sleep disrupts sleep, even if a person can fall asleep easily.