Do you feel like you turn into a sloth every afternoon when the clock strikes 3? If you ate a bagel for lunch, a drop in blood sugar may be to blame — but that’s not the only culprit behind your sudden sluggishness. In fact, there might be a legitimate, biological reason for the infamous ‘mid-afternoon slump’ — and your circadian rhythm might just be behind it.
Also known as our ‘biological clock,’ our circadian rhythm is basically the cascade of body processes that controls when we wake up and go to bed (or at least feel energized and sleepy). Lightness and darkness signal a part of our brain (the hypothalamus) that it’s either time to wake up or go to sleep, triggering our production of certain hormones and other bodily changes that either rev us up or quiet us down.
Our body produces the stress hormone cortisol when it’s time to wake up, and melatonin when it’s time to go to sleep. Our body temperature also warms up to wake us up and cools to make us feel sleepy.
“These factors that trigger our circadian rhythm are called zeitgebers,” says Dr. Anil Rama, adjunct clinical faculty-member at the Stanford Center for Sleep Sciences and Medicine. In addition to lightness and darkness, eating, exercising and following various work or school schedules can also influence our biological clock. (Even feeling warm or cold has an impact!)
Our exact individual rhythms can vary, but most of us feel a strong shift and urge to wake up after sunrise and go to bed after sunset.
Though we might think our circadian rhythm only kicks in to make us tired after the sun goes down, we actually also experience a natural dip in the afternoon. This mid-afternoon slump that leaves you sitting at your desk in a daze is totally normal. In fact, most of us experience a biological clock shift sometime from 1–4 p.m.
Some cultures throughout history have embraced this circadian shift and built their daily lives around it, Rama says. Taking a siesta — the mid-afternoon break from work, business and school is still practiced throughout Spain — for example.
A drop in body temperature, which increases melatonin production, is the primary culprit of this mid-afternoon dip — but working a desk job may also contribute, since our body associates stillness with sleep. “This shift in your circadian rhythm is typically just a fraction (about, say, 1/3) as strong as the shift that occurs at nighttime,” says Rama. Still, you might feel less sharp than you do in the morning or have some trouble focusing.
However, if you’re sleep-deprived (whether because you stayed up too late watching Netflix, have a newborn at home or have a condition like sleep apnea), your mid-afternoon slump may feel more like a mid-afternoon crash to a halt.
“If you feel like you could knock out in the afternoon, and it’s affecting your ability to do your job or live your life, consider seeing a sleep specialist,” Rama says. You may need to reevaluate your schedule and sleep hygiene, and investigate any health issues that may be impacting your circadian rhythm.
Otherwise, how to deal with your mid-afternoon slump varies.
“If you can take a quick, 20-minute nap, go for it,” says Rama.
If a nap isn’t in the cards, warm yourself up by getting up for a walk or stepping outside to snag a few minutes of sunshine, he suggests.
Other options: Put on some upbeat music or grab yourself a glass of water (dehydration can also contribute to feeling tired).
To minimize that slump in the first place, set a timer to remind yourself to stand up and stretch or walk around at least once every hour.