State of sleep from which it is difficult to awaken. It is represented by slower brain waves called delta activity on the EEG. It is a type of NREM sleep and is called stage 3 on sleep studies.
Delta sleep is stage four of the deep sleep cycle. This is necessary to feel well rested. to increase the Delta waves during sleep, regular exercise is the only method. Of course, exercise has other benefits.
Delta
Stage 4 sleep. Stage 3 also often emits delta waves.
Delta sleep is the first sleep to be made up after sleep has been lost. Stage 4 sleep.
It is an album enhanced with Delta binaural beats to lull you to sleep and engage lucid dreaming states.
Delta
Delta
There is alpha or stage one sleep, theta or stage two sleep, delta or statge 3 sleep, and alpha with REM (stage 4 sleep).
Delta waves
Delta waves
delta
Stage 4 sleep.