Scientists Just Made a Surprising Discovery About the Sleep Quality of Heavy Caffeine Users

3 min readNew research suggests caffeine can change sleep.Researchers discovered that people slept more deeply in one phase of sleep when they drank a lot of caffeine.But according to sleep medicine physicians, the findings don’t suggest caffeine is good for sleep.When you’re trying to make it through the day on short sleep, it only makes sense to reach for something caffeinated...sometimes more than once a day. And while sleep medicine specialists have made it clear that too much caffeine can make it harder to get good rest, sometimes desperate times call for desperate measures.Now, recently published research from the Journal of Psychopharmacology suggests there may be a slight upside to having a lot of caffeine: It could improve one area of sleep.There are a lot of caveats to these findings, and all signs continue to suggest that you should dial back on caffeine if you drink a lot in your day-to-day. But if you’re already coming off of a bad night of sleep and are sipping coffee to help you ride out the day, it’s good to know there’s a slight silver lining. Here’s what the data show, plus what doctors want you to keep in mind.Meet the experts: Beth Malow, MD, a neurologist and chief of the Division of Sleep Disorders at Vanderbilt Health; and W. Christopher Winter, MD, a neurologist and sleep medicine physician with Charlottesville Neurology and Sleep Medicine.What did the study actually find?For the study, researchers analyzed data from more than 485,000 people who participated in the UK Biobank and 1,700 people from the HypnoLaus cohort. The UK Biobank is a long-running biomedical database, while the HypnoLaus cohort is a Swiss study that includes data on genetics, caffeine intake, and sleep, among other things.After analyzing the data, researchers found that participants’ sleep-quality ratings and whether they identified as a morning or evening person didn’t depend on how much caffeine they drank in a day. According to the statistical models used in the analysis, they discovered that consuming four or more caffeinated drinks (such as coffee, tea, and soda) was associated with shorter total sleep time than those who drank three or fewer a day.But there was a surprising catch: People who drank a lot of caffeine had more non-rapid-eye-movement sleep (NREM) depth compared to those who had less. (NREM sleep depth is how deeply a person sleeps as they transition from light sleep to deep sleep.)Basically, while people who drank more caffeine didn’t get as much total sleep, they ended up sleeping more deeply at some point in the night. In conclusion, the researchers wrote that “the data show that high habitual caffeine intake alters the characteristics of sleep in the general population, while sparing the major physiological principles of sleep-wake regulation possibly due to adaptation.”Is caffeine better or worse when you have sleep issues?It’s easy to interpret these findings as having more caffeine is better for your sleep, if you know you can’t get enough sleep. But sleep medicine physicians say that’s definitely not what’s going on here.The increase in NREM sleep is likely “a compensatory mechanism to overall decreased sleep from caffeine use,” says Beth Malow, MD, a neurologist and chief of the Division of Sleep Disorders at Vanderbilt Health.And keep in mind, the study still supports that high caffeine use is linked to a drop in sleep time, says W. Christopher Winter, MD, a neurologist and sleep medicine physician with Charlottesville Neurology and Sleep Medicine.Dr. Winter notes that the findings don’t exactly mean that you’ll end up with more intense REM sleep if you drink more caffeine. “Sleep deprivation often creates a more intense REM sleep pattern—often referred to as REM rebound,” he says. People who are sleep-deprived usually have deeper and more consolidated sleep because they’re trying to make up the sleep they’ve been missing, Dr. Winter says.There is some takeaway hereUnfortunately, it’s not that drinking more caffeine will help you sleep better. Instead, Dr. Winter says the data still supports the “sage advice” sleep medicine experts have been sharing for years: “Drink your coffee early and in reasonable amounts, and give yourself adequate time at night to sleep.”And, if you’re craving deeper sleep, Dr. Malow recommends exercising more. “That has been shown to increase sleep depth,” she says.Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health. She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter. Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.