female trying to stay awake while studying

—Larry, Centre County, Pennsylvania

Falling asleep in class is often caused by sleep debt.

Sleep debt is what you accrue when the quality (or quantity) of your sleep isn’t sufficient to your need. This is usually because of inadequate time spent sleeping, but may also be due to subconscious sleep interruptions.

Your brain wants 8–10 hours of sleep a night with the same bedtime each night and wake time each morning. Anything short of this becomes sleep debt that your brain looks to recover at the earliest opportunity. (Now you know why you can sleep almost nonstop the first three days of vacation.)

Alertness varies during the day. Roughly speaking, we’re most alert about 4 hours after waking up and again about 12 hours after waking up, with a drowsiness trough about 8 hours after waking up. So for instance, if you get up at 7:00 a.m., trying to study at 3:00 p.m. is likely to lead to nodding off. If you are waking up feeling unrested or are routinely falling asleep during the day, check in with your school nurse or with your health care provider.

The treatment for sleep debt is sleep. The more you sleep, the better you concentrate. The better you concentrate, the more easily you form memories (which then get locked in during sleep). The more easily you form memories, the less time you need to study. Sounds easy, but we all know it can be tough to make it a priority.

Try these tricks to help you stay awake:

Switch up when you study

Try to study at times you’re most alert. As a general rule, the later at night you study, the poorer the quality of your learning.

Switch up where you study

Sometimes it’s helpful to be in a quiet place without distractions. Other times it’s helpful to be in a busy environment where you have to tune everything out. Change it up.

Switch up how you study—physically

Pay attention to your study posture and shift from sitting to standing to avoid the dreaded hunch and all of its associated pain.

Plan breaks

Study hard for 45 minutes, then reward yourself with 15 minutes of something else. I suspect you’ll get a lot more done this way, even though you’re “spending less time studying.” We all respond to incentives, and efficiency is not to be overlooked.

Still getting stuck in a slump? Try a power nap or mini workout

If you always crash at a particular time, consider a quick nap or short workout to help you feel more alert. Just be sure your nap takes place before 3 p.m. (when possible) to avoid messing with your sleep later.