he is kinda on the right track, but TECHNICALLY he is wrong.
theres 4 sleep stages, not just the ones he is outlying
awake is the presence of 50% or more alpha waves
stage 1/2 is less than 50% alpha with the rest in the theta waves, with mixed frequencies
stage 3 is delta waves also called Slow Wave Sleep and/or deep sleep where we release 80% of the days hgh and testosterone, and also counter stressor hormones like cortisol which is high during periods of the day, basically bringing things back to normal and restoring the body and immune system.
THEN we have REM sleep, theta mixed frequency with rapid eye movements, like stage 1 but much cleaner.
and this cycle is approx 90 mins so he gets this part right and the next part that; as the night starts we have our biggest stage 3 block, and our smallest REM block.
the 2nd cycle the stage 3 block is 1/2 of the first and the REM block doubles.
the 3rd cycle the stage 3 block 1/2 again and the REM block doubles again... see the trend?
i hope this cleared up some technical mistakes he made, which explain the REAL way a textbook case of someone sleeps.