You know you’ve been there, sitting at your desk a few hours after lunch, struggling to keep your eyes open and yawning every few minutes. You might reach for an energy drink or chug your fourth cup of coffee for the day, but that only makes you jittery and anxious — and you still want to go home.

Sound familiar? If so, you’re not alone, and there’s a good explanation for why you get tired in the afternoon. It has to do with your circadian rhythm—your body’s signals for the sleep and wake cycle.

While the afternoon slump isn’t fun, it’s completely natural. Your circadian rhythm tends to make you sleepy in the afternoon, usually between 1 p.m. and 4 p.m. During that time, you might struggle to stay focused. You might even deal with symptoms like mood swings, headaches, and stomach aches.

For some, drinking another cup of coffee might not be the best idea, whether because of caffeine sensitivity or worries about sleeping at night. Thankfully, there are things you can do to fight back against this daily slump and boost your energy throughout the afternoon. Try to improve your sleep hygiene every night, eat a nutritious diet, take quick naps when you can, and reduce stress as much as possible.

You can also benefit from getting plenty of exercise each day. If you’re tired and sluggish, you might not feel like hitting the gym, but even a walk around your neighborhood (or office) can improve blood and oxygen flow and help you feel more alert.

You’re not alone if you’re struggling with the afternoon slump every day. Remind yourself that it’s normal and natural, and use some of these tips to give yourself a healthy boost without relying on so much caffeine. Of course, if you’re concerned about your sleepiness, always reach out to your doctor.