Let me start right off saying that I absolutely love coffee. So much so that regulating how much I consume has been a struggle over the course of my life. It is a powerful tool for productivity and quality of life. Writing something to demonize coffee is something I would not be likely to do. That having been said, we should all make sure to consciously regulate both how much of it we drink and when. So let’s talk about how it works.
There are two mechanisms that control sleep: adenosine and circadian rhythm. Let’s address the latter first.
Circadian rhythm regulates many of your bodily functions over the course of a day. Simply put, it makes you feel sleepy when the sun starts to go down and wake you up when the sun comes up. Assuming that you keep a schedule in which you sleep for 8 hours a night and are awake for 16 hours during the day, your circadian rhythm will determine WHICH 8 hours are the sleepy ones. Different people’s bodies want different things with regard to sleep schedule but most people fall within a certain standard deviation.
Adenosine is the second part. From very early in your day adenosine starts to build up, and binds to adenosine receptors in your brain. As more adenosine attaches to these receptors you will experience an increase in sleep pressure. Build up enough sleep pressure and you fall asleep on the couch. Ideally you would get into bed shortly before that is maxed out so you will sleep soundly through the night.
Caffeine works by attaching itself to the adenosine receptors so you will feel less sleepy. It can even knock adenosine off of a receptor it’s already attached to, which is why a cup of coffee late in the evening can perk you right back up when you just felt like you were ready to go to bed. Of course, the adenosine that has been displaced doesn’t go away. As your body processes the caffeine out it will open those receptors again and the adenosine will rush in to take its rightful place. That is why a caffeine boost will wear out and be replaced with a crash.
As such, caffeine can be an incredible tool if you didn’t sleep well the night before or if you are perhaps having a dip in energy in the afternoon. The problem is that every drop of coffee that goes into your system has to be processed out. Give yourself plenty of time and your body will take care of that easily. But if there’s not enough time between the intake of caffeine and bedtime you will find yourself having trouble sleeping. The rule of thumb that has always worked for me is to give myself 6 hours between drinking a caffeinated beverage and going to bed.
And for those of you who claim immunity to caffeine, I give my usual response. Try what I’m recommending and then just see what happens. and if you happen to be an absolute coffee fiend who just can’t go without, try switching to decaf after 2 p.m. You will find many sources that Warn that decaf still has caffeine in it, which is true, but the amount is inconsequential in my opinion. A regular cup of coffee typically has around 100 mg of caffeine in it and a cup of decaf has between 5 and 10.