These are the current best selling sleep trackers at Amazon.

SaleBestseller No. 3
Fitbit Flex 2, Black (US Version)
4075 Reviews
SaleBestseller No. 15
Amazfit Equator Activity + Sleep Tracker
239 Reviews

Details and pricing last updated at 2018-10-21 at 09:44 . Links and images via Amazon Product Advertising API