Coffee, or at least the caffeine we get from coffee, is one vice (or drug, by the definition of many) that doesn’t carry much guilt societally. The greatest struggles most of us encounter with its daily consumption either come in the form of it adding unnecessary daily calories to our diets (for those of you who drink sugary lattes and heavy creamers) and the way it sometimes interferes with our sleep at the end of the night. 

The conscious coffee drinker knows that its caffeine can take as much as 12 hours for the body to metabolize, meaning that drinking it too late or too often throughout the day is a quick recipe for staring at your ceiling with the lights out in the middle of the night. Ironically, while it can be a healthy part of your diet when consumed in specific ways as well as giving us a great boost early in the day, interfering with our sleep patterns will inevitably pose greater health risks than it’s all worth. 

But as mentioned, many of us already know this. We try to avoid caffeine past certain hours of the day, thinking that a “coffee curfew” is our magical ticket to a good night’s rest. Somehow, this doesn’t seem to work though. We’re still left tossing and turning through the night unsure of what’s keeping us up. 

According to new research published in the journal Sleep, if you consume either nicotine or alcohol regularly, those are the things you should be cutting back on rather than coffee. Specifically, researchers now recommend we should cut ourselves off from either at least four hours before bedtime, as they actually have a greater ability to disrupt our sleep than coffee. Led by researchers at Florida Atlantic University (FAU), Brigham and Women’s Hospital, Harvard University, Emory University, the University of Mississippi Medical Center, and the National Institutes of Health, the study focused on the evening consumption of alcohol, caffeine, and nicotine among 785 African-Americans over a combined 5,164 days. They measured sleep patterns using wristwatch-like devices while participants provided daily entries in sleep diaries. Even when controlling for stress, age, and even gender, using nicotine or alcohol within four hours of sleep had the greatest impact on their sleep cycles. And if a participant already struggled with insomnia, nicotine was all but guaranteed to cut another 40 minutes of sleep out of each night. And don’t think you’re fooling your body by vaping, for example. Researchers said any form of nicotine consumption, including smoking, vaping, and dipping, will interfere with sleep. 

“African Americans have been underrepresented in studies examining the associations of nicotine, alcohol, and caffeine use on sleep,” Christine E. Spadola, Ph.D., lead author of the study and an assistant professor in FAU’s Phyllis and Harvey Sandler School of Social Work, said in a press release. “This is especially significant because African Americans are more likely to experience short sleep duration and fragmented sleep compared to non-Hispanic whites as well as more deleterious health consequences associated with inadequate sleep than other racial or ethnic groups.”

And contrary to what we believe about coffee, this study actually suggested that coffee consumption in that four-hour window actually didn’t interfere with sleep cycles — at least according to their specific data. As long as we don’t consume pitcher after pitcher of coffee throughout the day, caffeine won’t have an adverse negative impact on our sleep, said one researcher. 

“In fact, heavy use of alcohol can permanently damage the genes involved in healthy sleep and wake cycles,” says Rose MacDowell, chief research officer at Sleepopolis. “A brain in withdrawal from nicotine may wake you up to satisfy its craving,” she said. “Because of its effect on the lungs and blood vessels, nicotine can increase breathing disorders that impact sleep, such as asthma and sleep apnea. Vaping may not involve the inhalation of smoke, but may deliver more powerful stimulant effects than smoked nicotine, disrupting sleep even further.”

As for alcohol, the nightcap is a popular tactic many employ for winding down at the end of the night. The truth is, a drink or two before bed is actually far more damaging to the quality of sleep you’re going to get than it is helpful. Nowadays, there’s plenty of science to back the suggestion that you should actually avoid that nightcap altogether for the sake of a good night’s sleep tonight as well as saving yourself from some long term health sacrifices to your health. 

First, research does support that alcohol reduces the amount of time it takes you to fall asleep and increases the amount of deep sleep you’ll get initially. Both these are positives on the surface but once those effects wear off, you’re actually facing a massive increase in sleep disturbances in the second half of the night. 

Take the concept of “sleep architecture,” for example, which organizes the order and variation of different stages of sleep: Rapid Eye Movement and Non-Rapid Eye Movement. There are typically four different stages of NREM followed by a brief period of REM, a process that repeats itself multiple times throughout the night as each REM period gets longer and longer throughout the night. With alcohol, however, alcohol decreases REM sleep overall, even delaying the first period of REM.

Now, a night of heavy drinking will throw all of this off entirely. As the liver metabolizes the alcohol, your sleepiness starts to wear off to the point that you’ll likely find yourself wide awake by 4 am. And even if you do manage to get back to sleep before the sun comes back up, don’t expect to get back to into a deep sleep again as you’ll be uncomfortably tossing and turning, sweating as a result of the vasodilation caused by alcohol. This is a process in which your blood vessels widen, warming the skin and calling your sweat glands into action. It will effectively cool you down but it will also raise the odds of even more sleep disturbances. 

Naturally, it seems the best solution to any of these problems would be to cut them out completely or significantly reduce our consumption. At the very least, researchers still recommend adhering to a strict cut off time leading into the evening if you regularly consume coffee, nicotine, or alcohol.