Does restricted sleep affect force control differently when people rely on sight or memory?

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Sleep loss is common and has consequences for physical and mental health. Although the effects of sleep restriction on working memory are well documented, its effects on continuous force control were unknown. The researchers set out to measure how sleep restriction affected the magnitude and variability of visually and memory-guided force production. They hypothesized that both would be impaired after sleep restriction.

Fourteen men took part in an eleven-day inpatient sleep study. They completed a grip force task after two nights with ten hours of time in bed per night at baseline, four nights with five hours per night during sleep restriction, and one night with ten hours during recovery. The task consisted of four 20-second trials of isometric force production using the thumb and index finger, targeting 25% of each participant's maximum voluntary contraction. In visually guided trials, participants received continuous visual feedback on their force. In memory-guided trials, feedback was removed for the last 12 seconds of each trial. In both conditions, they were instructed to maintain the target force.

After sleep restriction, participants produced less force in the visually guided condition, but not in the memory-guided condition. The researchers suggested that visual attention tasks may be more affected by sleep loss than memory-guided tasks. Participants who reported feeling more alert after sleep restriction and recovery sleep produced higher force in the memory-guided condition, but not in the visually guided condition. The researchers suggested that perceiving decreased alertness may lead to greater attention to the task during memory-guided visual tasks.