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.