Updated October 30, 2026. An earlier version of this page gave a wake-time timing chart and said waiting for cortisol to fall makes coffee "hit harder." We could not find a primary study that shows that, so this version sticks to what published sources say about cortisol, caffeine and sleep.
"Wait 90 minutes after waking before your first coffee" is popular advice, built on the idea that morning cortisol is already doing the waking-up job. It sounds neat. The research behind it is thinner than the advice suggests. Here's what is known about your cortisol rhythm, how long caffeine lasts, and when caffeine affects sleep, so you can make your own call.
Why coffee timing comes up at all
Your body runs on a roughly 24-hour clock, and cortisol is one of the hormones that follows it. According to MedlinePlus, from the U.S. National Library of Medicine, cortisol levels are normally highest in the morning and much lower around 4 p.m. Cortisol helps the body respond to stress and control blood glucose, among other jobs. The early-morning rise has a name in research: the cortisol awakening response.
What is the best time to drink coffee in the morning?
There is no well-established best minute. The "wait until cortisol falls" idea is a theory based on the daily cortisol curve. We could not find a primary study showing that delaying your first coffee gives a bigger or better effect than drinking it on waking, so treat any specific window you see online, including the 90-minute rule, as a preference rather than a finding.
What is well documented is how caffeine itself behaves. MedlinePlus says caffeine reaches its peak level in the blood within one hour, and you may feel its effects for four to six hours (MedlinePlus). If you like coffee in bed at 6 a.m. and it works for you, nothing here says you're doing it wrong.
Does coffee actually change cortisol?
One 2026 study looked at this directly. Boscaini and colleagues (Nature Communications, 2026) had 31 regular coffee drinkers stop coffee for 14 days, then go back to caffeinated or decaf coffee for 21 days. The cortisol awakening response did not change during the break from coffee. After coffee was reintroduced, the caffeinated group had lower cortisol on waking. It was a small study, with 15 or 16 people per group at the end, so it is one data point rather than a rule. More on that study in Coffee and Gut Health: What a 2026 Trial Found.
Should you wait 90 minutes after waking to drink coffee?
If you want to try it, the honest framing is an experiment, not a fix. Some people feel jittery or anxious after an early cup. MedlinePlus lists restlessness, anxiety and a fast heart rate among the effects of too much caffeine, and the FDA notes that people vary widely in how sensitive they are to caffeine (FDA). If that sounds like you, try a different time or a smaller amount and see how you feel. If your current routine works, keep it. Persistent symptoms are worth raising with a doctor.
When should you stop drinking coffee before bed?
This is where the evidence is clearer. In a study published in the Journal of Clinical Sleep Medicine in 2013, Drake and colleagues gave 12 healthy sleepers 400mg of caffeine at 0, 3 or 6 hours before bedtime. Caffeine taken even 6 hours before bed reduced objectively measured total sleep time by more than one hour, and participants were apparently unaware of the disturbance. The authors suggested that caffeine generally should be avoided after 5 p.m. to allow healthy sleep (American Academy of Sleep Medicine).
The American Heart Association's 2026 scientific statement on caffeine also notes that caffeine can disrupt sleep in some people (AHA news release). If you sleep on a different schedule, such as after a night shift, the same idea applies: count back from when you plan to sleep. More in our night shift guide.
Is it bad to drink coffee on an empty stomach?
MedlinePlus notes that caffeine increases the release of acid in the stomach, which can sometimes lead to an upset stomach or heartburn. Some people find a cup on an empty stomach uncomfortable and others don't. On brewing method, a 2018 study in Scientific Reports found that cold brew and hot brew had comparable pH, while hot brew had higher titratable acidity (Rao and Fuller, 2018). That is a property of the brewing method, not a remedy. If you have a digestive condition, talk to your doctor. More in Is Cold Brew Healthy?
What you drink is half the equation
Timing is one variable. What's in the cup is another. The AHA statement says that adding sugar, flavored syrups, milk or cream to coffee likely reduces its potential health benefits. The FDA explains that the Daily Value for added sugars is 50 grams a day on a 2,000 calorie diet (FDA), so the Added Sugars line on a label is worth a look. For how much caffeine is in different cold brews, see how much caffeine is in cold brew.
And count your total. FDA says up to 400mg a day is an amount not generally associated with negative effects for most healthy adults, and some conditions and medications make people more sensitive to caffeine. More in How Much Caffeine Is Too Much?
The simple version
The morning timing rule is a preference, not a proven finding, so drink your first coffee when it works for you. The evening side has better evidence: in the sleep study above, caffeine 6 hours before bed still cut sleep by more than an hour, and the authors suggested avoiding caffeine after 5 p.m. on a typical schedule.
Frequently Asked Questions
What is the best time to drink coffee?
There is no proven best time in the morning. Cortisol is normally highest in the morning, and some people prefer to wait a while after waking, but we could not find a primary study showing that waiting gives a better effect. The clearer evidence is about the evening: caffeine taken 6 hours before bed reduced sleep in a 2013 study.
Does coffee raise cortisol?
The evidence here is limited. In one small 2026 study, the cortisol awakening response did not change when regular coffee drinkers stopped coffee for two weeks, and people who went back to caffeinated coffee had lower cortisol on waking.
How many hours before bed should I stop drinking coffee?
In a 2013 Journal of Clinical Sleep Medicine study, 400mg of caffeine taken 6 hours before bed reduced total sleep time by more than one hour. The authors suggested avoiding caffeine after 5 p.m. for healthy sleep.
Is it OK to drink coffee on an empty stomach?
For many people it's fine, but MedlinePlus notes caffeine increases stomach acid release, which can sometimes cause an upset stomach or heartburn. If you have a digestive condition, talk to your doctor.
Sources
- MedlinePlus. "Cortisol Test." U.S. National Library of Medicine.
- MedlinePlus. "Caffeine." U.S. National Library of Medicine.
- American Academy of Sleep Medicine. "Late afternoon and early evening caffeine can disrupt sleep at night" (on Drake C, et al., Journal of Clinical Sleep Medicine, Nov. 15, 2013).
- Boscaini S, et al. Nature Communications. 2026;17:3439.
- Rao NZ, Fuller M. "Acidity and antioxidant activity of cold brew coffee." Scientific Reports. 2018;8:16030.
- American Heart Association Newsroom, news release on the 2026 scientific statement "Caffeine and Cardiovascular Disease."
- U.S. Food and Drug Administration. "Spilling the Beans: How Much Caffeine Is Too Much?"
- U.S. Food and Drug Administration. "Added Sugars on the Nutrition Facts Label."
This article is general information, not medical advice. Bare Brew is a coffee drink, not a treatment for any condition. Each 12 fl oz can has 320mg of caffeine. It's not recommended for children, people who are pregnant or nursing, or anyone sensitive to caffeine. If you take medication or have a health condition, talk to your doctor about caffeine.
