prophylactic napn.
A daytime nap taken to prevent tiredness later in the day.
Example Citation:
"Dr. David Dinges, a sleep researcher at the University of Pennsylvania, is a strong advocate of prophylactic nappingtaking what he and others call a 'power nap' during the day to head off the cumulative effects of sleep loss."
Jane Brody, "New Respect for the Nap, A Pause That Refreshes," The New York Times, January 4, 2000