 So I can't say what's tracking it, but it will tell me if I'm in restorative sleep, REM sleep, you know, if I'm just going into my sleep. It tells me at what point I exactly fall asleep. It shows me my heart rate through the night. And knowing your heart rate through the night is a good thing because some people might have sleep problems where they stop breathing in the middle of the night, and that's going to send your body into stress.