First and foremost, don’t try to circumvent your boss to make it easier. Not only will this piss them off, but makes your shit stink even worse. Call early, as early as you’re comfortable with. This serves two purposes:
1) You’re going to sound a little horse and awkward having just woken up.
2) Less chance of pissing off your boss for some last-minute bullshit.
Also, keep it short. Once you have confirmation, get off the phone.