Mixed
Psychomotor vigilance performance recovers during sleep in a saturating exponential manner with a time constant of approximately 2.14 hours, meaning the first few hours of sleep provide disproportionate recovery benefits compared to later hours.
If you are sleep-deprived, prioritize getting at least 2 hours of sleep. Your cognitive performance (reaction time, vigilance) recovers most rapidly during these first few hours. Extending sleep beyond 5-8 hours yields diminishing returns for immediate performance recovery, so focus on getting that initial rest rather than stressing about perfect 8-hour durations if you are short on time.
We found that the DRCs to each PVT metric improved in a saturating exponential manner, with recovery rates that were similar [time constant (T) ≈2.14 hours] for all the metrics.
Why this rating
Cross-study comparison of controlled laboratory experiments with consistent protocols, though limited to young healthy adults.
Source
Dose-response Relationship Between Sleep Duration and Human Psychomotor Vigilance and Subjective Alertness
Megan E. Jewett et al. · SLEEP · 1999
DOI 10.1093/sleep/22.2.171
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