What are sleep phase shifts?

Sleep phase shifts are when your body’s clock moves forward or backward, like changing the time on a toy watch.

Imagine you have a favorite stuffed bear that tells you when it's bedtime. One night, the bear says, “It’s 9 o’clock, time to sleep!” But the next night, it says, “It’s 10 o’clock, time to sleep!” That means your body clock has shifted forward by an hour.

Or maybe one day you go to bed at 8 o’clock and wake up at 7 o’clock. The next day, you go to bed at 9 o’clock and wake up at 8 o’clock. Your body clock is moving backward, like sliding a puzzle piece into a new spot.

Sometimes this happens when you change your schedule, like going to school or having a weekend sleepover. It’s like telling your body: “Hey, let’s try sleeping later today!” or “Let’s go to bed earlier tomorrow!”

When your body clock moves, you might feel a little wobbly, just like when you ride a swing and it goes higher and lower. Your brain is getting used to the new time.

Eventually, your body says, “Okay, I get it now!” and everything goes back to normal.