Yes, you’re slightly taller when you wake up in the morning! This is because, as you sleep, your spine decompresses. Throughout the day, gravity compresses the discs between the vertebrae in your spine, which reduces their thickness slightly. By nighttime, this compression can make you a bit shorter.
While sleeping, your spine relaxes, and the discs between the vertebrae rehydrate and regain their thickness, restoring your height. The difference is small—usually a few millimeters to about a centimeter—but it’s real! This extra height is temporary, though, as gravity gradually compresses your spine again during the day.