This is AWESOME! Ever wonder why some mornings you'll wake up feeling refreshed after not much sleep, and other mornings you'll feel groggy, even if you slept a ton?

Its because you're waking up in the middle of a sleep cycle! I'd heard that before, but never knew I could really plan around it.

CHECK THIS OUT. Its called the Sleepy Time Bed Calculator and it tells you when you need to go to bed depending on when you need to wake up.

For example, I said I need to wake up at 4:15. Here are my results:

So if I'm in bed around 10 p.m., I will probably fall asleep by 10:15, and that means 6 glorious hours of sleep and I won't wake up mid-sleep cycle.