What are the stages of your sleep cycle?

There are mainly four stages of the sleep cycle. Stage 1 lasts about 5-10 minutes. Stage 2 lasts around 20-30 minutes, and people could have stage 2 a couple of times in the same night. The deep sleep portion is called Stage 3 and Stage 4. While Stage 3 can last about 20 minutes, Stage 4 can last about 45 minutes on average. There is another stage called Rapid Eye Movement or REM sleep, which can last around 90 minutes.