Research
Hormonal
Caffeine consumption alters sleep architecture by increasing the duration and proportion of light sleep (N1) and decreasing the duration and proportion of deep sleep (N3/N4).
Even if you don't feel tired, caffeine may be stealing your deep sleep. Expect about 11 minutes less deep sleep and 6 minutes more light sleep per night if you consume caffeine close to bedtime. This reduces the restorative quality of your sleep, contributing to next-day fatigue.
WeakSupportsHIGH confidence
Duration (+6.1 min) and proportion (+1.7%) of light sleep (N1) increased with caffeine intake and the duration (-11.4 min) and proportion (-1.4%) of deep sleep (N3 and N4) decreased with caffeine intake.
Why this rating
Meta-analysis of 18 studies reporting sleep architecture.
Source
The effect of caffeine on subsequent sleep: A systematic review and meta-analysis
Carissa Gardiner et al. · Sleep Medicine Reviews · 2023
DOI 10.1016/j.smrv.2023.101764
Meta-analysis · 24 studiesCited 273×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Caffeine consumption reduces total sleep time by an average of 45 minutes and decreases sleep efficiency by 7%, with the magnitude of sleep loss increasing as the dose increases and the time of consumption approaches bedtime.Weak
- Caffeine increases sleep onset latency by approximately 9 minutes and wake after sleep onset by approximately 12 minutes.Weak
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