What is the sleep cycle?

Throughout the night, you’ll cycle into light sleep, deep sleep, light sleep and then REM. You have about four to five of those cycles throughout the night and as you sleep, you gradually get less and less deep sleep. Deep sleep is thought to be the more regenerative aspect of sleep that’s associated with human growth hormones and memory abilities. If you get less deep sleep, it’s associated with a 40-percent decline in memory performance.