What they're saying: The sleep you get in the hours before waking is "rich in rapid eye movement" or REM sleep, said Rebecca Robbins, sleep researcher and lead author of a new study at Mass General Brigham study focused on the snooze button. REM sleep is important for emotional processing and learning.

• But the sleep you get in between alarms is typically lighter, Robbins said, leading to what researchers call "sleep fragmentation."

By the numbers: Using data from 21,000 users of the Sleep Cycle app, researchers found that more than half of sleep sessions logged ended in a snooze alarm.

• On average, users spent 11 minutes snoozing.
• 45% of participants hit snooze on more than 80% of mornings.

The bottom line: To feel more rested, "set your alarm for the latest possible time, then commit to getting out of bed when your first alarm goes off," Robbins said.