How much caffeine is too much? Well, the super short answer is around 400mg per day for the average adult. That answer does absolutely no justice to caffeine though.
Pour yourself a cup of your favorite java and let me take you on a caffeine journey and how caffeine is working in your body.
Does caffeine give you energy?
How many think caffeine gives them energy? It does give that impression, but it’s is actually just playing tricks on your brain. I am going to get all sciency (is that a word? who cares? We aren’t supposed to believe science anymore).
The cells in your brain, as they do their little jobs throughout the day like remembering where you put your keys and making sure to pick the kids up after school, produce a waste product called adenosine. Your brain is filled with special receptor sites for adenosine. Just think of it as chairs. It’s easier. When all the chairs are filled up, you feel really tired and ready to sleep. As you sleep these adenosine guys and girls get booted and the chairs are open to start the day and you feel refreshed.
If you don’t get a enough sleep, some adenosine loafers stick around and some chairs are filled right when you wake up. Hence, the groggy feeling.
Where does caffeine fit into this? Well, caffeine butt looks a lot like an adenosine butt. This means caffeine can take adenosine’s spot on that special receptor site. This keeps adenosine circulating in your blood, but you won’t feel as tired as you should because adenosine needs to be in it’s chair to tell your brain its tired. Eventually, caffeine’s butt goes numb and it leaves the receptor site. Like a violent game of musical chairs adenosine rushes in and fills those spots.
That ladies and gentlemen is what we call the Caffeine Crash.The boost in energy you feel is your body releasing cortisol and norepinephrine in response to the caffeine.
Is it ok to have coffee at night?
Caffeine doesn’t affect me. I can fall asleep just fine. And right you are!!As you learned, caffeine blocks adenosine from fitting into it’s receptors to make you feel sleepy. So how is it you can fall asleep after drinking caffeine at night?
There are 2 factors for falling asleep. Your sleep drive and your circadian rhythm. Your sleep drive is the like your battery for the day. As your battery drains, your sleep drive (need for sleep) increases.
Your circadian rhythm is your own personal clock system that all your cells and body systems use to know when stop or start body processes.For many people they are running on empty most of the day keeping themselves propped up on caffeine, stress, and sugar. They are so tired at the end of the day and their sleep drive is so high they crash into bed.
But what kind of sleep are they getting? Even though they are asleep and probably have built up a tolerance to the feeling of caffeine’s effects it is still there and still having an impact on their body.They most likely are experiencing these below the surface
– slightly increased heart rate
– cortisol and norepenephrine elevated which suppresses their melatonin levels and when they are secreted
– altered brain wave patterns
– increased core body temp
How does caffeine impact sleep?
Ok, but I’m sleeping isn’t that the main goal? Yes, but your sleep is going to be mainly light sleep. It is sleep, but not the great restful and restorative deep sleep cycle your body needs. This starts a negative feedback loop. You wake up exhausted, hitting the snooze button 5x, before peeling yourself out of bed making a bee line to the coffee maker to just start being a human again.
You are tired because you missed out on a large part of your deep sleep and melatonin dose. Then all day you are riding the caffeine rollercoaster. Perk up, crash, perk up crash all the while hitting up that big bowl of Halloween candy you swear is for handing out. Then you crash into bed to do it all over again.Yep, you can fall asleep after having coffee at 8pm, but zoom out and see how that cycle is playing out during your day.
Caffeine half life aka how long does caffeine last
I would like to explain how your coffee this morning could still be in your system tomorrow morning. To start we need to define what a half life is.
Half- Life- no that is not how long 2020 is taking. It is a time frame for something to break down to half it’s initial value. Caffeine for the average person has a half life of around 5 hours to reduce it’s amount by 50%.
Now this value could be longer if you are a slow metabolizer of caffeine or are older. 10 hours after drinking your morning coffee you still will have 25% of the caffeine in your blood system.
Here is how it plays out.7am Joe has his coffee. For simple math lets say it has 100mg of caffeine in it.
Around noon he has 50mg of caffeine in his blood.
On the way home at 5pm he has 25mg of caffeine left
At 10pm he has 12.5mg of caffeine still circulating as he is trying to get ready for bed.But let’s be honest for a second, I see Starbucks with a line pretty much all hours of the day.
Say 11am Joe grabs another cup of coffee. This has another 100mg of caffeine.
4pm he has 50mg left in his system.
9pm he has 25mg left
But wait, Joe had his afternoon crash at 3pm so he had one more cup of stale office coffee clocking in at 100 mg.
At 8 pm he has 50mg from this coffeeAt 11pm he has probably around 35mg from it.
So if you are still following me here, let’s add up where each of those coffees are at 11pm. 1st Coffee = 10mg2nd Coffee = 20mg3rd Coffee = 35mgGrand Total = 65mg of caffeine while he is trying to fall asleep the equivalent of half a cup of coffee at least.
Conclusion
Now I oversimplified this, but hopefully you get the picture. Caffeine stays with you for a while and is still messing with your sleep long after you drank it.Try to finish your coffee by 12pm. You can look up the caffeine content of your coffee as this will vary depending on how it was roasted and variety. Time you have it and the total amount both play a role in how much is left at night.That crash between 1-3pm you get is normal. Everyone has it because it is your circadian rhythm dip. To offset this, go outside without sunglasses and get some bright light exposure instead of another cup of coffee.
If you would like to learn how to live the best 1/3rd of your life enroll in Build Better Sleep’s Invest in Sleep program.
