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.
To understand sleep deficiency, it helps to understand how sleep works and why it's important. The two basic types of sleep are rapid eye movement (REM) and non-REM. Non-REM sleep includes what is commonly known as deep sleep or slow wave sleep. Dreaming typically occurs during REM sleep. Generally, non-REM and REM sleep occur in a regular pattern of 3â5 cycles each night. Your ability to function and feel well while you're awake depends on whether you're getting enough total sleep and enough of each type of sleep.