to caffeinate or not to caffeinate?

bad news! there might be some pros to skipping that late afternoon cup of coffee...

While drinking coffee might be the most common way to combat sleepiness, caffeine can be found in anything from soft drinks and energy drinks, to chocolate bars and caffeine pills - all of which can have serious consequences when it comes to trying to sleep.

For instance, even though opting for a decaf coffee removes about 97% of the total caffeine - it’s important not to ignore decaf drinks as a small source of the natural stimulant, too. 

Interestingly, caffeine is considered the most popular stimulant in the world, with over 100,000 metric tons ingested per year (1). But what exactly makes caffeine so stimulating to us? And how does it affect our sleep, our brain, and our wellbeing in both the long and short term?

How caffeine gives us energy via the brain

When caffeine first evolved in plants it served two primary functions:

Higher quantities of caffeine, such that can be found in the leaves and seeds of particular plant species, are extremely toxic to insects, helping ward off any hungry bugs from destroying the plant. Like a built-in security system!

In lower quantities, like we find in the nectar of certain flowers, caffeine can actually serve the opposite purpose. When insects like bees and butterflies get a caffeine buzz from the plants they choose to pollinate, it acts as a subtle marker in their brain so they’ll be more likely to return again. A win-win for the plants and the bugs!

In the human body and brain, however, caffeine works slightly differently. The reason why so many of us can depend on coffee to keep us awake - or help us get out of bed in the first place - has everything to do with a molecule called adenosine (2). 

Adenosine is one of the body’s key sleep-inducing molecules. It’s what’s known as an inhibitory neuromodulating and has a depressant effect on activity of the central nervous system. 

In other words, it makes us sleepy by slowing things down. When adenosine bings to chemical receptors in the brain, it reduces the speed that neurons fire, and lowers dopamine (a neurotransmitter associated with motivation and reward (3)). 

Caffeine on the other hand, is an adenosine receptor antagonist. Think of an “antagonist” like a school bully. An “adenosine antagonist” is a bully that steals adenosine’s seat in class. In this analogy, the receptors in our brain are the seat. 

But because these receptors are not designed to be activated by caffeine molecules, the slowing down, sleepy-effect we would typically experience with adenosine never occurs; instead, we become stimulated with caffeine, our dopamine levels begin to rise (reward and motivation), and we feel wide-awake and ready for the day. 

Any coffee drinker knows this feeling well! Not to mention that caffeine can have some pretty amazing additional benefits, too. 

Over time, regular caffeine consumption can reduce the risk of neurodegenerative diseases, increase how long we live, and improve the body’s natural metabolism and ability to burn fat - especially when taken prior to any kind of workout (4). 

In the short term, caffeine makes us feel happier and more alert, but it can also increase anxiety, blood pressure, and even our heart rate if too much is consumed for that particular individual. 

Not to mention the effects of caffeine on insomnia. 

how caffeine affects our sleep

The human brain is an incredibly complex and adaptive thing. In fact, it has no problem adapting to a frequent, high consumption of caffeine. 

When our brain realises that adenosine’s seat is constantly being stolen by big bully caffeine, it simply produces more receptors (seats) to accomodate! This is why even with plenty of caffeine around, it is possible to sleep.

But being able to sleep and sleeping well are two very different things.

Research studies have shown that caffeine taken even 6 hours before bedtime can have significant disruptive effects on sleep onset, sleep quality, sleep duration and slow-wave (deep) sleep throughout the night (5, 6, 7). 

A cross-sectional study that examined 15,686 American adolescents found that individuals reporting high caffeine intake were more likely to be tired in the morning than those reporting a low intake. This suggests that not only that the time we consume caffeine has a direct impact on our wellbeing (both while asleep and awake), but also that watching how much caffeine we consume can be important (8).  

Because caffeine and coffee consumption is associated so strongly with reducing fatigue, researchers propose that there is a cycle taking place; tired people drinking caffeine everyday, only to end up more tired - and in need of more caffeine - in the long run. 

This also explains why, over time, we may need to increase the amount of caffeine we consume in order to maintain the initial level of alertness we felt, and why caffeine withdrawals can be such a headache - literally. 

conclusion on caffeine 

While some research implicates caffeine in the enhancement of issues and disorders related to sleep, many research experiments claim that the “net benefits” outweigh the cons. 

Ultimately everybody is unique, and even what works best for you at one point in your life, might not be what works best for you down the line. 

As a general rule of thumb, try to cut-off your consumption of caffeine a minimum of 6 hours before you aim to go to sleep. You may find that a longer period of caffeine-absence before bed minimises your sleep problems even more. 

Additionally, if you find yourself struggling with chronic or acute insomnia, headaches, or anxiety attacks, this could be a sign that you are ingesting too much caffeine. Trouble falling asleep, staying asleep, or suffering from sleep-related anxiety can also be a few of our body’s warning signs that caffeine might not be for us. 

For more information on other factors that may be contributing to a poor night’s sleep, check out our article on “the brain-science of sleeplessness,” or visit the sofi treehouse to share your thoughts and learn from the experiences of your fellow Pioneers. 

Text references:

1. Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992 May-Aug;17(2):139-70.
2. O'Callaghan, F., Muurlink, O., & Reid, N. (2018). Effects of caffeine on sleep quality and daytime functioning. Risk management and healthcare policy, 11, 263–271.
3. Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992 May-Aug;17(2):139-70.
4. Sc, Y., & Muralidhara (2016). Beneficial Role of Coffee and Caffeine in Neurodegenerative Diseases: A Minireview. AIMS public health, 3(2), 407–422. 
5. Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 9(11), 1195–1200. 
6. Weibel, J., Lin, YS., Landolt, HP. et al. The impact of daily caffeine intake on nighttime sleep in young adult men. Sci Rep 11, 4668 (2021).
7. Reichert CF, Veitz S, Bühler M, Gruber G, Deuring G, Rehm SS, Rentsch K, Garbazza C, Meyer M, Slawik H, Lin YS, Weibel J. Wide awake at bedtime? Effects of caffeine on sleep and circadian timing in male adolescents - A randomized crossover trial. Biochem Pharmacol. 2021 Sep;191:114283.
8. O'Callaghan, F., Muurlink, O., & Reid, N. (2018). Effects of caffeine on sleep quality and daytime functioning. Risk management and healthcare policy, 11, 263–271.