Why you get tired in the afternoon
Feeling sleepy in the early afternoon is normal for most people. When to see a doctor, what makes the dip deeper, and what to write down for a week.
Most afternoon slumps are normal, and short sleep or late coffee can make them worse. A few need a doctor, so check the list below first.
When the afternoon slump is worth seeing a doctor about
Some daytime sleepiness has a medical cause that a change in schedule won't fix. Talk to a doctor if any of these apply to you:
- You've nodded off or drifted out of your lane while driving, or come close. Don't drive drowsy until you've been checked 1.
- Someone has told you that you snore loudly, stop breathing, or gasp or choke in your sleep. These are common signs of sleep apnea, along with morning headaches and feeling very sleepy during the day 2.
- You're very sleepy during the day even though you regularly get seven or more hours in bed.
- You fall asleep at times you didn't choose, like in conversation, at meals or in meetings.
- The sleepiness is new or getting worse, or comes with low mood, weight changes or other symptoms.
Why the slump happens
How alert you feel depends on two things. One is sleep pressure, which builds the longer you're awake. The other is your body clock, which pushes back against that tiredness for most of the day but eases off in the early afternoon. Many people feel that as a slump somewhere in the early to mid afternoon.
It gets called the post-lunch dip, but researchers have seen it in people who had no lunch at all 3. Feeling slower at 2:30 p.m. doesn't mean something is wrong with your sleep or your schedule. If the slump passes in half an hour and you can keep working, that's normal. If you're fighting to stay awake at your desk most afternoons, go through the doctor list above.
How short sleep affects the afternoon slump
Most adults need seven hours or more 4. If you get six hours on weeknights, you start each afternoon already sleepier.
Can coffee after lunch make you more tired?
Caffeine keeps you from feeling sleepy for a few hours, but it doesn't make up for the sleep you're missing. A 3 p.m. coffee can cut into that night's sleep without you noticing, and then you're more tired the next afternoon. The guide to the 90-minute coffee rule covers how long caffeine stays in your body and when to have your last cup. Try having your last coffee earlier for a week and see if the afternoons change.
Keep a one-week log of your afternoon slump
Before changing anything, keep a short log for seven days. Write it at the time rather than trying to remember at the end of the week. A note on your phone is enough, and it's useful to take along if you do see a doctor later.
Each day, note:
- Roughly what time you fell asleep and woke up
- How rested you felt on waking, from 1 to 5
- Every caffeinated drink and when you had it
- What you ate for lunch and when
- When the slump hit, how long it lasted, and how bad it was from 1 to 5
- Whether you got outside or moved during the day
- Anything unusual, like a late night, a drink in the evening, a child up in the night or a big deadline
At the end of the week, read it back. You might find your worst afternoons follow your shortest nights or a late coffee the day before, or that the slump was milder on days you got outside at lunch. Big lunches or long afternoons in a dim room can show up too.
Change one thing at a time so you can tell what helped. If the bad afternoons line up with short nights, more sleep is the first thing to try, and the guide to fixing your sleep schedule covers how to move it. If you've spent most days indoors, try getting morning light.
When to see a doctor
If the slump keeps getting worse, or any of the signs at the top of this page apply to you, talk to a doctor.
Turn this into a plan for your day.
Answer a few questions about your schedule and light access, and Calibrate builds a daily light-timing plan around the day you actually live.
References
- National Highway Traffic Safety Administration. Drowsy driving. www.nhtsa.gov/risky-driving/drowsy-driving
- Mayo Clinic. Obstructive sleep apnea: symptoms and causes. www.mayoclinic.org/diseases-conditions/obstructive-sleep-apnea/symptoms-causes/syc-20352090
- Monk TH (2005). The post-lunch dip in performance. Clin Sports Med 24(2):e15-e23. doi.org/10.1016/j.csm.2004.12.002
- Watson NF, Badr MS, Belenky G, et al. (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. J Clin Sleep Med 11(6):591-592. doi.org/10.5664/jcsm.4758