Why does coffee make me sleepy!?

Why does coffee make me sleepy!?

Many of us need our coffee to get our day started – that lovely buzz from caffeine is so loved and essential! However, one thing that you might notice is that you get a bit sleepy or extra tired after drinking coffee (or really anything with caffeine). Have you ever wondered why? 

Well, caffeine is a stimulant – specifically of the central nervous system. It helps you feel awake and more alert – especially if you’re already fatigued. Caffeine works in the body by taking the place of where adenosine binds to receptors in your brain. Adenosine is what makes you sleepy and helps your body to slow down. When you have caffeine in you, it binds to the receptors that adenosine would usually bind to – which means adenosine can’t sneak in and make you sleepy! Your body takes about 45 minutes to absorb caffeine from your coffee, and then usually sticks around for up to 6 hours!

If you consume caffeine every day, eventually your body becomes tolerant of it and it lessens the effects of your usual caffeine buzz. Interestingly, a study by Lara et al. (2019) found progressive tolerance to caffeine over a 3-week period. They tested a person’s increase in aerobic exercise after caffeine consumption – and found a progressive increase in performance in the first few days! However, this performance enhancement was gradually lost as the participants consumed the same amount of caffeine each day compared to a placebo group that got no caffeine. This study really shows how quickly our bodies can become used to caffeine!

Now, what happens when the caffeine is gone? Once the caffeine is gone (or metabolized) from your body, adenosine is then able to bind to those receptors and can work to start slowing the body down and making you sleepy. Sometimes people refer to this sleepiness (and irritability!) as a ‘caffeine crash’. So, how can you avoid this? Well, one way is to spread out your caffeine consumption. You can sip on your coffee over a few hours to maintain your caffeine levels – or even split your drinks into more cups! This also helps you from consuming a bunch of caffeine really quickly – and making your caffeine crash even worse! It is also important to stay hydrated (because dehydration can also make you tired and grumpy!). Doctors recommend you not consume more than 400 mg of caffeine in a day – an 8oz cup of coffee can contain anywhere from 90-200 mg of caffeine – so limiting yourself to 2-3 cups of coffee per day is a safe place to be for most of us!

Do you have any tips or tricks to share with us to avoid caffeine crashes!? We’re always looking for new things to try!

Nap on,

Kerri Lynn 


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