Time magazine reported on June 12 [1944] that âas far as the U.S. Army can determine, the first use of D for Day, H for Hour was in Field Order No. 8, of the First Army, A.E.F., issued on Sept. 20, 1918, which read, âThe First Army will attack at H-Hour on D-Day
The best way to fall asleep regularly is to make sure your sleep cycle is regular. If you don't know your schedule, or how long you should sleep for: 1  For two weeks, go to bed at the exact same time. 2  Get out of bed when you wake up in the morning â don't hit snooze or keep sleeping.
The brain cycles through five distinct phases during sleep: stages 1, 2, 3, 4, and rapid eye movement (REM) sleep. REM sleep makes up about 25% of your sleep cycle and first occurs about 70 to 90 minutes after you fall asleep. Because your sleep cycle repeats, you enter REM sleep several times during the night. During REM sleep, your brain and body are energized and dreaming occurs.