Sleep restriction significantly impaired isometric contraction endurance and specifically reconstructed brain functional networks, with alterations in the SMN-DMN connection in the theta frequency band emerging as the most critical indicator for dissecting the impact of SR on motor performance.
Sleep restriction significantly reduced the duration of sustained isometric contraction to exhaustion of the biceps brachii muscle.
EMG analysis revealed significant decreases in median frequency (MF) and average power frequency (MPF) before exhaustion following sleep restriction, indicating onset of muscle fatigue.
During resting state after sleep restriction, brain network connectivity was generally enhanced in the theta, beta, and gamma-1 frequency bands, particularly in the central executive network (CEN).
During the motor task after sleep restriction, brain network connectivity strength in the theta, alpha, and beta frequency bands was generally decreased, disrupting sensorimotor integration.
Principal Component Analysis identified functional connections centered around the default mode network (DMN) and network efficiency as representative neural markers of sleep restriction's effect on motor performance.
Under normal sleep conditions, strength of connections within SMN and between SMN-DMN in the theta frequency band was negatively correlated with duration of muscle contraction, but this correlation weakened or reversed following sleep restriction.
The functional integration of the DMN and the connection mode of the SMN were identified as key neural markers through which sleep restriction affects motor performance.
This research suggests that getting less than 4 hours of sleep significantly undermines physical endurance performance, specifically the ability to sustain a muscle contraction. In the study, 35 athletes performed a biceps curl held at moderate intensity until they could no longer continue, once after a normal night of sleep (more than 7 hours) and once after being sleep-restricted to fewer than 4 hours. After poor sleep, participants gave out sooner, and electrical signals from the muscles showed earlier signs of fatigue. Importantly, the study used brain wave (EEG) recordings to show that sleep restriction does not simply 'turn down' brain activity uniformly — instead, it reshapes how brain regions communicate with each other in specific ways depending on whether the person is at rest or actively moving. At rest after sleep restriction, certain brain networks — particularly those involved in executive control — showed increased connectivity in several frequency ranges. But during the actual physical task, brain connectivity dropped in the frequency ranges most associated with coordinating sensation and movement. This suggests that a sleep-deprived brain may be working harder at rest but struggles to efficiently organize neural communication when it is needed most, during physical effort. The connection between the sensorimotor network (which coordinates movement) and the default mode network (which is typically active during rest and self-referential thought) in the theta frequency range was identified as the single most informative indicator of how sleep restriction impairs motor performance. This research suggests that sleep loss does not just make muscles tire faster — it fundamentally changes how the brain networks responsible for movement planning and execution talk to each other. For athletes and coaches, this implies that sleep quality may be a critical and underappreciated factor in neuromuscular performance, and that brain connectivity patterns could potentially serve as objective markers of sleep-related performance impairment. Future research might explore whether specific recovery strategies can restore these neural communication patterns.
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Upload Your LabsZhu C, Peng T, Song J, Chi A, Wei X, Chi P. (2026). Changes in athletes' brain network connections during isometric muscle contractions after sleep restriction.. International journal of psychophysiology : official journal of the International Organization of Psychophysiology. https://doi.org/10.1016/j.ijpsycho.2026.113371