Researchers have investigated whether the body is truly disconnected from the external world during sleep. To do so, they focused on how heartbeat changes when we hear different words during sleep.

A new study reveals that while we sleep, our brains quietly sort through the day’s experiences, keeping what we intend to remember and letting emotion-driven moments drift away. Study: Top-down ...

There's a term for that sleepy, almost-drunk feeling — it's called sleep inertia, says Dr. Seema Khosla, a sleep medicine physician and the host of Talking Sleep, a podcast from the American Academy ...