Sleep onset is defined by three consecutive epochs of stage 1 or one epoch of any other sleep stage.
Caution in interpreting reports: The Compumedics software report identifies sleep onset as three consecutive epochs of sleep regardless of the stage. This may rarely cause a discrepancy between the identity of sleep onset, sleep time, and sleep latency as defined using the conventional approach used by the scorers (sleep onset as 3 epochs of stage 1 or one epoch of any other sleep stages) versus the output of computer generated reports.