Both stages have delta waves in the same range but induce different effects on the brain. They're both characterized by the same measure for depth (of sleep).

Both stages have delta waves in the same range but induce different effects on the brain. They're both characterized by the same measure for depth (of sleep). To clarify with more, specific information: http://en.wikipedia.org/wiki/Slow-wave_sleep http://en.wikipedia.org/wiki/Slow-wave_sleep