BY THE OPTIMIST DAILY EDITORIAL TEAM
That mid-afternoon latte might feel like the boost you need to power through your to-do list, especially when the days are short and the weather begs for something warm. But before you cozy up with a seasonal peppermint mocha at 4:00 p.m., it’s worth asking: will this cup of comfort sabotage your sleep tonight?
The answer is not one-size-fits-all, but experts agree on one thing: timing matters. The effects of caffeine last longer than many people realize, and depending on your body, that pick-me-up could be pushing your bedtime back more than you think.
If you want to enjoy your coffee and get better sleep, here’s what to know about how caffeine works, how long it lingers, and when it’s best to call it a day.
How much caffeine are you really drinking?
First things first: not all caffeinated drinks are created equal. An eight-ounce cup of brewed coffee contains about 95 milligrams of caffeine, while the same amount of black tea has closer to 47 milligrams. If you’re sipping espresso, you’re getting about 62.8 milligrams per ounce, which adds up quickly in double or triple shots.
Even the way your coffee is brewed can affect caffeine levels. Factors like brew time, grind size, water temperature, and serving size all play a role.
In other words, that cozy latte may have more buzz than you bargained for.
Why caffeine timing affects your sleep
Caffeine works by blocking adenosine, a chemical that builds up in your brain throughout the day and makes you feel sleepy. This blockage increases alertness but at a cost.
“Caffeine has a long half-life in most adults, which means it stays active in the body for five to seven hours,” explains Dr. Lynette Gogol, a board-certified neurologist and lifestyle medicine physician. “That 3:00 p.m. coffee might still be circulating at bedtime, interfering with your brain’s natural ability to wind down.”
You may think you’re in the clear once the jitters wear off, but that’s not always the case. Jane Leverich, MS, RDN, a registered dietitian, says caffeine can still silently disrupt sleep by delaying melatonin, interfering with your circadian rhythm, and lowering sleep quality.
Even smaller amounts can make a difference. While under 100 milligrams of caffeine earlier in the day may not wreck your sleep, higher doses like the 300 to 600 milligrams found in several cups of coffee can reduce the deepest, most restorative stages of sleep, says Dr. Gogol. One study even showed that caffeine consumed six hours before bedtime could shorten sleep time by over an hour, even in people who felt like they slept fine.
So, when should you stop drinking coffee?
The magic cutoff time will vary depending on your body and your bedtime, but experts recommend a six to eight hour caffeine buffer before sleep. So, if you usually head to bed around 10:00 p.m., aim to finish your last cup by 2:00 to 4:00 p.m. at the latest.
Some people may need even longer. According to Dr. Gogol, caffeine clearance slows with age, during pregnancy, with liver conditions, or with certain medications like oral contraceptives or H2 blockers.
Your genes can also affect your sensitivity. Some people have CYP1A2 gene variants that break down caffeine faster, while others have ADORA2A variants that make their brains more sensitive to caffeine’s effects. “These differences explain why one person can sleep soundly after a 5:00 p.m. espresso, and another lies awake from a noon cappuccino,” Dr. Gogol explains.
Can some people handle coffee later in the day?
Yes, but it depends on your unique biology. “Some people metabolize caffeine quickly, so it clears their system faster,” says Dr. Gogol. Others may be more sensitive due to genetics, health conditions, or medications, and that means even a small cup can throw off their sleep.
That said, even fast metabolizers aren’t off the hook with high daily intake. Consuming more than 300 milligrams per day can still reduce sleep quality over time, regardless of your genes.
The final verdict
If you love coffee but also value sleep, paying attention to when you drink it can make a big difference. A good general rule is to avoid caffeine within six to eight hours of bedtime. And if you deal with insomnia, anxiety, or find yourself waking up in the middle of the night, an eight to ten hour buffer may be even better.
Caffeine is not the enemy, but a bit of strategy goes a long way. By knowing your limits and staying on top of your timing, you can enjoy your daily cup without sacrificing your nightly rest.
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