REM Cycles

Im very confused with this. When do REM cycles happen? Are they the same for everyone? Why does it change when you take a nap? I would like to increase my chances for a Lucid Dream, and if I am correct, knowing your REM cycles increases chances!

Please answer!

REM happens every 90 minutes.

I don't think it changes when in a nap. It should be the same.

here is some more info on sleep stages.

I think what he means by changes, is what we discuss on WBTBs.

REM cycles can "change" if you skip one by not getting a full nights rest. For example, when you follow a Polyphastic Sleep pattern, pull an all nighter, or do a WBTB, you're avoiding a necessary REM period which will become active next time you sleep. This is called REM Rebound, and it can cause longer and more intense REM periods.

The WBTB technique utilizes this.