Ok sleep has two primary groups REM (R) and NON-REM (NR). NR sleep is when most of your deep sleep is done. This period can have dreams but not typicly. R sleep occurs after going through NR sleep for a while. The typical time for rem to start is after 5-6 hours of sleep. Setting an alarm then will help. It also is very helpful to have an organized sleep schedual. If you set the alarm for 5 bourse of sleep and it wakes you up durring s dream you know your in Rem sleep.