For me it's kinda the opposite.
When I need to wake up early for school My body rolls out of bed.
When I can sleep in on weekend,
" IT'S 4:00 AM, RISE AND SHINE, DIRTBAG! "
My Ability to sleep when Tomorrow is School; My Ability to Sleep on Weekends; My Ability to Sleep when there is a Big Day tomorrow, And i need a-lot of sleep.