We would be hard pressed to find someone who doesn’t indulge in a little caffeine intake here and there. It’s in coffee, tea, chocolate, soft drinks, and the big bad energy drinks that are so commonly consumed. But what is it doing to our sleep? The answer isn’t that surprising.
Our great local Université de Montréal published a study that underlines the impact of caffeine consumption on sleep. This study demonstrated that caffeine impacts the “criticality” of the brain. To keep it simple, too much activity and there is chaos, too little, and there is nothing. Criticality is the middle point between these two states, where the brain is functioning at an optimal level.
The thing is, by consuming caffeine too close to bedtime, you are pushing your brain beyond the criticality zone where it is more alert. Sounds good, right? Well, if your goal is to get to sleep, not so much. While this state is useful during the day, it may be what is causing your restlessness.
“The results showed that caffeine increased the complexity of brain signals, reflecting more dynamic and less predictable neuronal activity, especially during the non-rapid eye movement (NREM) phase of sleep that’s crucial for memory consolidation and cognitive recovery”. Essentially, you are hindering your brain’s ability to get into that deep, restorative sleep that is required for your body and mind’s recovery. Simply put, when you drink a coffee, or a soft drink close to bedtime, you might not enter the proper sleep stages that facilitate your body’s natural recovery processes.
On top of it all, it was suggested that the younger you are, the more susceptible to these changes in brain processes that you are as well. Whether it be tolerance, or simply your brain being naturally more susceptible to the stimulant that caffeine is, the risk remains that the younger you are, the greater the impact of caffeine on your sleep.
When I was in my mid-20’s, I would typically drink 5 coffee’s a day, that would lead well into the night so I could be alert while studying. Now I realize my folly in such activities. To get the best, most restorative sleep possible, it might be better to cut the caffeine intake at about noon to 2pm so that there is little to no caffeine in your body when 9-10pm rolls around. This is even more important for our younger population, who are often up late into the night, but remain at a critical point in their lives to reap the benefits of sleeping well.
Ultimately, what you want to do from here remains your choice, but I know for myself, I will no longer be having that 5pm coffee to keep me going into the evening, because I know it’s half-life and I know how important sleep is to overall wellbeing. The question is, what are you willing to change in your life to give yourself the most favorable of outcomes?
Reference:
Arcand-Lavigne, M, Carrier, J, Frenette, S, Lajnef, T, Jerbi, K & Thölke, P,. Caffeine induces age-dependent increases in brain complexity and criticality during sleep. Communications Biology, 2025; 8 (1)
Alexandre G. McGovern 