Why Are Teenagers So Lazy in the Mornings?

You can blame them for a messy bedroom, but you can’t scold teens for their reluctance to get out of bed in the morning—their body clocks are changing.

During the tumultuous teen years, hormones are surging and the body is changing dramatically. Meanwhile, large swathes of the brain are rewiring (see Why Has My Teenager Turned into an Alien?).

One of the side effects of this biological turmoil is that a teenager’s body clock moves forward. As a result, they become more inclined to go to sleep later and also wake up later. They aren’t just being lazy—their body really is in a different time zone! For a typical 16-year-old, 10 p.m. feels like your 8 p.m., and a 7 a.m. alarm carries the pain of an adult’s 5 a.m. disturbance.

No one knows exactly why the adolescent’s body clock makes this two-hour shift, but it’s an inescapable result of the child brain maturing into an adult one. Interestingly, similar changes happen after puberty in other animals, including monkeys and mice.

When a teenager lives in a world of 8:30 a.m. starts, they will become progressively more sleep deprived—going to sleep late yet still being forced to get up at “adult time.” When the weekend comes, it’s normal for teenagers to have marathon sleep-ins to try to compensate.

A teenager’s brain tends to be foggier during the morning, so some schools have experimented with later start times and moving the most mentally taxing subjects to later in the day. This has generally proved successful, with attendance rates, sickness, and academic performance all improving.

So go easy on teens—for a number of years, they will be going through a perpetual jet lag of sorts. The body clock is at its latest when you get to 20, and thereafter it slides back with each passing year.

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shifting sleep times

As you age, your body clock shifts back and forth. For most of your life, you tend to go to sleep between 9–11 p.m. and wake at sunrise. However, throughout the teen years, the body clock temporarily changes to run much later.