Internal clock
An internal clock was an individual's automatic time regulation system based on daily cycles.

In 2365, six-hours-ahead-Jean-Luc Picard's internal clock realigned as time progressed closer to his origin point. ()

In 2367, measurements at the cellular level lead Beverly Crusher to conclude that the crew of the  had lost consciousness for longer than thirty seconds, as was previously believed. ()

See also 
 Internal chronometer

External link

Time
Physiology