Recent research suggests that the boundaries between sleep and wakefulness are often blurred, particularly when we are sleep-deprived.

State dissociation — the presence of more than one vigilance state* concurrently — is more common than anyone previously suspected, researchers suggest. Parts of our brain might be going offline without us even realizing it, possibly because the brain’s cortical columns fall asleep independently when they become tired.

Forgetfulness and daydreaming could be examples of this, but so could more bizarre and even criminal behaviors.

* The three states of vigilance: awake, rapid eye movement (REM) sleep, and non-REM (NREM) sleep.