Sleep Consistency is going to bed and waking up at the same time in order to preserve a consistent circadian rhythm. By swiping down on the Sleep Page in the app and clicking on 'Time in Bed' on the bottom right, you can see your Consistency in the graph. Sleep Consistency is based on your previous 4 nights of Sleep.
Sleep is segmented into four stages (Slow Wave Sleep, REM Sleep, Light Sleep, and Wake), each of which serves a unique purpose.
Slow Wave Sleep (SWS) is an intense, active phase of Sleep. In this phase, the body repairs and regenerates tissues, builds bone and muscles, and strengthens the immune system. Because of its role in muscle and bone repair, this is a particularly important Sleep Stage for athletes. It is common for SWS to occur more, and in longer bouts, at the beginning of the night than at the end. Over the course of the night, SWS accounts for 17-20% of total sleep time.
REM is the Sleep Stage in which memory consolidation and dreaming occur. REM periods increase in length as the night progresses. The first REM period usually occurs about 90 minutes after you first fall asleep, and lasts only 10 minutes. For young, healthy adults, a normal amount of REM sleep is 60-100 minutes or roughly 22-26% of the night.
Light Sleep typically accounts for roughly half of the total Sleep time. Light Sleep primarily serves as a transition stage between Slow Wave Sleep and REM.
Wake comes in two forms – Sleep Latency is the time it takes you to fall asleep (which is not trackable when using auto sleep detection). Normal sleep latency is roughly 5-35 minutes. Sleep Disturbances are short periods of wake throughout the Sleep episode. For members, anywhere from 10-20 disturbances over the course of Sleep is normal. Most people experience more frequent disturbances as time in bed increases. In total, Wake (not including sleep latency) can account for around 10% of the total time in bed.
To learn more about Sleep Stages, check out our Locker Post: How Much Time Should You Spend in Each Stage of Sleep?