Deos REM sleep wears off?

After I wake up, how many hours does the effect of REM sleep lasts? I wake up at 6 am to go to class and come back home at 2 pm and Ive been trying to WILD when I get home but so far it has only worked once. My problem is that I don't know if it's not working because Im new to lucid dreaming or because the effect of REM wore off by 2 pm.

Ive heard 5 hours is the maximum. In reality i think it it a little less. Porbably depends how long you've been sleeping. (longer the sleep, longer the potential rem sleep afterwards)