Sleep-wake cycle is a way of describing the process of sleep because sleep is not just on or off. You’re not asleep all of a sudden. Sleep has different cycles, different levels of sleep.

There is light sleep, slow wave sleep, deep sleep, and rapid eye movement or REM sleep. And then you cycle around. Basically, sleep is a process.

Sleep-wake cycle can be described as a washing machine. So sleep is not simply on/off. And we think your brain washes away toxins during non REM (NREM) cycles.

This is one reason why you shouldn’t worry if you don’t remember your dreams because this cleansing of your brain happens during non REM sleep. And dreams take place during REM sleep.