Android: Alarm Clock Xtreme was in the running for our top Android alarm app. Now, it's added a sweet new feature that allows you to track your sleep habits over time, on top of the usual alarm features. Alarms and sleep trackers seem like they would go together like peanut butter and jelly, but it's hard to find an app that does both well. Alarm Clock Xtreme says it can now track your number of sleep cycles, time spent in REM sleep and how many times something disturbed you during the night. It also gives you a handy score for each night's sleep so you can see how much your sleep schedule is affecting you over time.