Sleep timers are available on a handful of devices that play music. Sleep timers automatically turn the music off after a certain amount of time has passed, so if you set a sleep timer for 60 minutes, the device will automatically shut off after 60 minutes as you fall asleep.
Unfortunately, when you open up the Alexa app on your phone, you’ll see the sleep timer card on the main screen, but it won’t show you how much time is left on the sleep timer unlike a regular timer can.
However, you can cancel the sleep timer at any point by simply saying, “Alexa, cancel sleep timer”.