It’s an idea that has been popularised by online influencers: avoid consuming caffeine for 90 to 120 minutes after waking up, they say, and you will perk up more naturally, thwart the dreaded afternoon slump and have better sleep. Proponents explain the idea as if it’s supported by good evidence, with some people who have tried the method saying it has “been a game changer” for their energy levels. How long caffeine keeps you sharp is partly based on your genetics.
Credit: iStock But scientists who study the relationship between caffeine and sleep say that while there may be some benefits to putting off your morning coffee, there’s not much research to back them up. In some cases, experts warn, the risks of delaying your morning caffeine could outweigh the purported benefits. How caffeine works, and how long it lasts Throughout the day, your body produces a chemical called adenosine, which binds to receptors in your brain and makes you feel drowsy.
Caffeine perks you up by blocking those receptors, says Marilyn Cornelis, a caffeine researcher at the Northwestern University Feinberg School of Medicine. Loading But you don’t feel the stimulating effects of caffeine immediately after your first sip of coffee, says Michael Grandner, the director of the sleep and health research program at the University of Arizona. It takes about 20 to 30 minutes for caffeine to be absorbed into your bloodstream, reach your brain and make you feel more alert, he says.
How long caffein.
