It's 4 o'clock, you can barely keep your eyes open and you have a difficult decision to make. Should you overcome fatigue (and possibly put the plant at your desk)? Or should you relax with a cup of coffee and possibly endanger the good night ?
It's a real compromise, and it's hard to know if it's worth making one. Here's how late you can drink coffee without affecting sleep.
How Caffeine Keeps You Awake
Let's give you a quick refresher on how coffee adds to its very special enthusiasm. Coffee contains the caffeine-known stimulant of the central nervous system . Caffeine works on a chemical in your brain called adenosine, neurologist and sleep specialist. Ajay Sampat M.D., assistant professor at UC Davis Health, says SELF. "Adenosine is like a sleep-inducing molecule that produces your brain while you're awake – the longer you're awake, the more adenosine is in your system," explains Dr. Sampat, and caffeine is essentially an adenosine antagonist Drs binds to adenosine molecules and reduces its sleep-inducing effects, Dr. says early and then for hours long after the initial excitement wears off.The primary stimulant effects of caffeine occur in the first hour or so when it reaches peak levels in your blood US National Library of Medicine : "Most people feel this burst of energy in the first 15 to 45 minutes," says Dr. Sampat.
However, it lasts a long time, long until caffeine is released Leave your system completely and the rapid side effects gradually diminish over time and your body metabolizes them, says Dr. Samp Typically, the half-life of caffeine, according to the Food and Drug Administration (FDA), is about four to six hours after consuming about half of the caffeine in your body system. At this point, you may still feel some of the stimulant effects of caffeine. Sampat. Then, another four to six hours later, half of that crowd is gone. If you drink a cup of coffee at 10 am containing 100 mg of caffeine (approximately an 8 ounce cup of coffee), you may still have 25 mg in your system if you lie down at 10 pm while drinking 200 mg At 4:00 pm
Whether or not there is some caffeine left in your system depends on a number of individual factors that affect your sleep. We will get it in a minute. In general, however, there is good evidence that for many people, caffeine can affect both the quantity and of sleep.
The primary effect of caffeine is that it is more difficult to fall asleep at first (also called longer sleep), Dr. Sampat. However, caffeine can also shorten the total sleep time by interrupting sleep throughout the night . "Caffeine can increase your rate of excitement-how often your brain wakes up every night, even though you may not remember," Dr. Sampat. This will make your sleep less efficient and may make you feel less relaxed in the morning. Caffeine can also affect the way you go through the different sleep stages, Dr. Sampat and reduces the time you spend in slow sleep, the deepest sleep phase. (There is also strong evidence that the more caffeine you drink and the later you drink it, the more likely it is that you sleep poorly at night, which makes sense given the elimination of half-life works.)  Why Caffeine Affects Everyone Differently
So that's the basic science of how caffeine can damage our sleep. But when it comes to how coffee affects one person's sleep compared to another person's IRL, that can be a whole different story. We all know someone who can crush two double espressos and whose effects seem insensitive, as well as someone who gets nervous after a cup of black tea. What is the problem? "Like almost everything else in sleep medicine, there's really just a lot of variability here," says Dr. Sampat. "There are so many different elements connected to it. Everyone reacts differently [caffeine]. "
We can limit much of that variability to genetics," Dr. Sampat. Our natural sensitivity to caffeine and the rate at which we metabolize it can vary greatly from person to person. Although we do not yet fully understand the genetic component, we know that there are genetic differences both in the various adenosine receptors targeted by caffeine, and in the major liver enzyme that metabolizes caffeine, cytochrome P450, explains Drs. Sampat. While the typical half-life of caffeine is four to six hours, this is far from true for all.
Then there are medical variables and lifestyle factors. We can shape our caffeine sensitivity with our caffeine drinking habits. The more caffeine we drink on a regular basis, the more we develop tolerance or diminished sensitivity – which means we need more and more to feel the effects. There are also certain medications that can interact with and influence the rate of caffeine metabolism. The liver enzyme cytochrome P450 metabolizes caffeine as well as other drugs (such as the beta-blocker propranolol). For example, if these liver enzymes are currently processing another drug while you are sipping a cold infusion, the caffeine will have to wait for it to be metabolized, prolonging the time it takes for the caffeine to reach you (and lose weight), Dr. Sampat.
It is also possible that the way caffeine affects you will change over the years. Many people find that their caffeine sensitivity increases with age. If it looks like you're suddenly betraying your evening espressos, you're probably not wrong. It is not clear why this happens, but it may be related to the same metabolic and genetic variations that we generally experience in caffeine processing, says Dr. Sampat. In any case, as people get older, they find it harder to fall and fall asleep Sampat, so that the stimulating effects of caffeine become clearer and more problematic.
What to do if you think about caffeine? keeps you up to date
Perhaps your past life experience indicates that you are one of the people who can drink coffee anytime and still sleep like a stone. If so, congratulations and do not change anything, you are perfect. "If you do not have trouble falling asleep and feel well rested during the day, [drinking coffee late in the day] is fine," says Dr. Sampat.
However, if you're curious to see if caffeine is going to keep you awake at night – or even convinced of it – then it's definitely worth experimenting a bit. Sleep is basic for good health, and if your 4 o'clock Latte affects it, you should be aware of it.
The first thing you want to tinker with is the time of day you stop drinking coffee. As a rule of thumb, Dr. Sampat, most people drink their last cup at least eight to ten hours before bedtime, so these two caffeine half lives have time to break down. This works until a shutdown time of about 12 to 14 clock. For most people, it's a simple policy to stop drinking coffee after lunch, Dr. Sampat. (If you think you could use the system by making all your coffee in the morning and early afternoon, then I have bad news for you, it will not work.) If you increase the amount of caffeine, that means more than Usually, your system will be included later, without the benefits of an earlier consumption.)
Given the different reaction of us all to caffeine, it may be helpful to follow "general guidelines, but try it on yourself and see what It influences, it's just to know, "says Dr. Sampat. In his experience, "It often takes a trial and error to find the right balance for a single patient. It really depends on the person. "You may be able to tolerate coffee until 10:00 pm or 4:00 pm, and your doctor can not tell you that." The other way to change your caffeine intake for better sleep is to reduce the amount. Drink one cup less a day and see what happens (or swap in a decaf that still contains a small amount of caffeine.) )
Dr. Sampat advises, step by step, regardless of the change made and / or "on days when you would like to do so" to be able to tolerate potential effects such as drowsiness, irritability, or headaches. (Not the day of a large work presentation.) "You can probably figure it out when the Changes help you to sleep better within a few days. "