Figure 2.14 | The Pattern of Sleep-Stage Cycles During a Night’s Sleep | After passing through the first four stages of sleep, we return through Stages 3 and 2 to enter REM sleep. This completes the first sleep-stage cycle. As this cycle is repeated throughout a typical night’s sleep, the deep sleep stages (3 and 4) get briefer and disappear, and the Stage 2 and REM sleep periods get longer.