How many dreams does the average person have per night?

People typically have 3 to 5 dream periods a night, mostly during REM sleep, which recurs about every 90 minutes and lengthens toward morning. Most dreams are forgotten within minutes of waking. When woken from REM, people report a dream about 80% of the time; from deep non-REM sleep, far less often.

Source: Dement & Kleitman (1957), Journal of Experimental Psychology; Nielsen (2000), Behavioral and Brain Sciences