I have to wake up tomorrow for a first tech rehearsal that starts (for me) at 8 AM and might last until 7 PM with pretty much no hope of me, as the stage manager, getting a lunch break. So I'm facing the dilemma of should I set a 6:30 alarm and have plenty of time for a shower and a hot breakfast, but get less sleep, or should I set a 7:30 AM alarm, have just enough time to eat a poptart and make some tea, and make it to the theatre maybe about 5 minutes late because who cares no one else actually has to show up until 8:30 anyway.
What's the science on how useful an extra hour of sleep is?