This study examined the impact of extended wakefulness on interoceptive accuracy and how individual differences in interoception related to subjective sleepiness.

Twenty-four healthy university students participated in the study. Interoceptive accuracy was assessed using the heartbeat-counting task during daytime and midnight sessions.

Interoceptive accuracy did not differ significantly between the sleep conditions. However, subjective sleepiness was negatively correlated with interoceptive accuracy at midnight.

Individual differences in interoceptive function may be associated with variability in perceived sleepiness under sleep pressure. These findings highlight the potential role of interoception in explaining why some individuals experience a mismatch between subjective and objective sleepiness.