I vote this. The 90 minute REM cycle is no joke.

My personal sleep therapy approach:

1. Deduct 30 minutes from when you need to wake up. Set one alarm for this time, one alarm for your normal time. If you do nothing else, do this. It’s awesome, trust me.
2. Deduct another 30 minutes then figure out how many 90-minute periods fit between now and that time. Go to bed at the beginning of one of those periods.
3. If you need to go to sleep 30 or 60 minutes earlier for some reason, add another “snooze” or two at the end.

What this does:

• Prevents getting up in the middle of REM, which is what causes you to feel like death even though you got enough sleep
• Gives you a 30-minute window to fall asleep first
• Wakes you up 30 minutes early in case something messed with your cycle and you feel like crap. Hitting snooze on your alarm clock gives you a bewildering 9-minute, 11-minute, or other arbitrary bit of extra sleep, but giving you a consistent 30-minute snooze period starts your morning with a reliable power nap instead of just gambling on your timing. You always wake up feeling good from a power nap.

Example: it’s 9 pm, I have to be up at 6. I set alarms for 5:30 and 6:00, then go to bed at 9:30 so I have 30 minutes to fall asleep, followed by 7.5 hours of sleep, which is 5 cycles. I wake up at 5:30, immediately kill the alarm, then wake up again at 6 and start my day.

Note: In general, I wouldn’t have three 30-minute snoozes. I’d just go to bed later. I try to avoid stacking two or more power naps at the end, but sometimes I will if I’m not going to be getting much sleep otherwise, like if I go to sleep NOW, I might get 3 hours.