How many sleep cycles should I get each night?

Most adults experience roughly four to six sleep cycles during a full night's sleep. However, counting cycles is less important than getting enough total sleep and maintaining a consistent schedule. Sleep cycles vary in length, commonly lasting around 80 to 100 minutes, and the balance of sleep stages changes throughout the night. Earlier cycles generally contain more deep sleep, while later cycles contain more REM sleep. Six estimated 90-minute cycles equal nine hours, while five equal seven and a half hours. These calculations can help with planning but are not exact. Do not deliberately reduce sleep simply to finish a whole number of cycles. Your daytime alertness, health and ability to wake comfortably are better indicators of whether you are sleeping enough.