microsleep

noun

1. (countable, uncountable)A brief period of sleep, usually of a few seconds, that may result from sleep deprivation or various medical conditions.

   “During a microsleep, your brain becomes blind to the outside world for a brief moment—and not just the visual domain, but in all channels of perception.”

   “It followed RAIB's conclusion that the driver of tram 2551 had lost attention for a period of several seconds before the accident, possibly due to going into a microsleep.”