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Exploring a Critical Threshold in Sleep Loss on Subsequent Evening Performance, Following Two Nights Partial Sleep
Ben Joseph Edwards1, Ellis Brotherton1, Adrian Markov1
1Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Brain and Behavior
|August 12, 2025
Summary
Sleep restriction impacts evening weightlifting performance, but a 60-minute nap can improve alertness and some strength measures, particularly for those with less severe sleep loss (SR3). However, grip strength remains unaffected by sleep restriction or naps.
Area of Science:
- Sports Science
- Sleep Research
- Human Performance
Background:
- Sleep restriction (SR) is known to impair cognitive and physical performance.
- The effects of varying degrees of SR on evening weightlifting performance and the potential benefits of napping require further investigation.
Purpose of the Study:
- To examine the impact of two nights of sleep restriction (4-hour vs. 3-hour sleep) on evening weightlifting performance.
- To determine if a 1-hour nap taken before evening weightlifting can mitigate performance decrements.
Main Methods:
- Thirty strength-trained males were divided into two SR groups (SR4: 4h sleep, SR3: 3h sleep) for two nights.
- Participants completed grip strength and bench press tests (1RM, peak power, peak velocity) at 5:00 p.m. after either no nap (N0) or a 60-minute nap (N60) starting at 1:00 p.m.
- Subjective measures of alertness, tiredness, and mood were also recorded.
Main Results:
- Sleep restriction (SR4 vs. SR3) significantly affected subjective measures of tiredness, sleepiness, and mood, with greater sleep loss leading to worse outcomes.
- While grip strength was unaffected, peak power and peak velocity in bench press were lower, and time to peak velocity was longer in the SR4 group compared to SR3.
- A 60-minute nap improved alertness and some strength measures (peak velocity) in the SR3 group but not in the SR4 group.
Conclusions:
- Sleep restriction demonstrates a dose-response effect on subjective well-being and mood.
- Bench press strength and grip strength appear resistant to the tested levels of sleep restriction.
- A 60-minute nap can partially restore performance and improve subjective states, but its effectiveness is contingent on the severity of sleep restriction.
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