Behavioral and brain responses to verbal stimuli reveal transient periods of cognitive integration of the external world during sleep
For a long time, it was believed that sleep was a state of complete disconnection from the outside world, where individuals were unresponsive to external stimuli. However, a study challenged this idea by examining how people react during naps. Researchers studied 49 participants, including those with narcolepsy and healthy volunteers, who were engaged in a word task during sleep. Surprisingly, participants showed behavioral responses, such as frowning or smiling, in most sleep stages, even in healthy individuals. These responses were more likely during periods of higher cognitive activity. This discovery suggests that there are moments during sleep when people can still react to the environment, opening up possibilities for studying sleep-related mental processes in real-time.
Türker, B., Musat, E.M., Chabani, E. et al. Behavioral and brain responses to verbal stimuli reveal transient periods of cognitive integration of the external world during sleep. Nat Neurosci (2023). https://doi.org/10.1038/s41593-023-01449-7