A cup of coffee is the first thing we reach for soon after we wake up. Right? For most of us, Coffee is our best friend with which we start our day. It comforts us, enhances alertness, fosters concentration, and improves mood and well-being. Research also shows that, on a long-term effect coffee can reduce the risk of depression, Parkinson’s disease, Alzheimer’s disease, cardiovascular mortality, and type 2 diabetes mellitus. [1] We rely on coffee’s caffeine, which is the game-changer since it acts as a psychostimulant on our nervous system, giving us the much-needed brain boost to start the day. [2]
Is there an "optimal time" for drinking coffee in the morning? Scientifically, that is still up for debate.
In the morning, adenosine levels are too low to be blocked by caffeine; thus, we do not see much caffeine effect. Additionally, your cortisol levels naturally rise in the morning, so you don’t need coffee right away to make you stay alert.
How Does Caffeine Affect Our Body? The Coffee-Adenosine Theory:
Caffeine is the most commonly consumed beverage in the world. As we take that first sip, caffeine gets absorbed and distributed swiftly throughout the bloodstream and it crosses the blood-brain-barrier, where it works by competitively opposing the action of adenosine, a hormone responsible for inducing sleep at the adenosine receptors A1 and A2A, which are widely distributed in CNS making us to stay awake and alert. [3] This is why many students during exams and working professionals rely primarily on caffeine to stay awake. During the day adenosine levels build up in the brain, making us feel more fatigued and drowsier, which is why you feel this crash before lunchtime or immediately after.
But interestingly the adenosine levels are usually low when you wake up. In simple words, when your brain works a lot during the day adenosine surges up making you feel more tired, and during the night your brain rests and adenosine drops down, that’s why you wake up fresh.
Research also shows that, on a long-term effect coffee can reduce the risk of depression, Parkinson’s disease, Alzheimer’s disease, cardiovascular mortality, and type 2 diabetes mellitus.
Cortisol and Circadian Rhythm:
Cortisol is a stress hormone that regulates your natural sleep cycle, also known as Circadian Rhythm. A study shows that lower levels of cortisol were seen at the beginning of sleep, while there was a rise towards the end of sleep, with the highest level reached at the moment the individual wakes up. [4] This is called Cortisol awakening response (CAR), the natural spike in cortisol levels across the first 30 to 45 minutes after morning awakening that helps us to start the day. [5]
In a recent video, Maddie Massy, MPhil, Immunology, working in collaboration with Innovation Lab team members shared an insightful explanation about the “Optimal time for Coffee in the Morning”
Naturally, in the early hours of the morning, our body functions differently, so it is best to avoid drinking coffee right after you wake up. At this time, adenosine levels are too low to be blocked by caffeine, and thus we do see not much caffeine effect. Additionally, your cortisol levels naturally rise in the morning, so you don’t need coffee right away to make you stay alert. In fact, drinking coffee too soon can interfere with the cortisol effects and leave you more tired later that day. Thus, experts suggest that delaying having your first cup of coffee by 1-2 hours after waking (typically between 9:30 AM-11:00 AM) helps you to stay awake and focused and can avoid afternoon slumps.
References:
"Start Your Day with a Morning Coffee!" European Heart Journal. Accessed December 26, 2024. https://www.zhh.ch/sites/default/files/zhh/2024/Files/Coffee_Morning_Editorial_EHJ.pdf.
"Coffee and Adenosine: The Science Behind Optimal Timing for Your Morning Brew." Wyatt and Freunde. Accessed December 26, 2024. https://wyattandfreunde.com.au/blogs/news/coffee-and-adenosine-the-science-behind-optimal-timing-for-your-morning-brew.
Ashihara, Hiroshi, and Alan Crozier. "Caffeine Consumption through Coffee: Content in the Beverage, Metabolism, Health Benefits, and Risks." Beverages 5, no. 2 (2019): 37. Accessed December 26, 2024. https://www.mdpi.com/2306-5710/5/2/37.
Gibbs, Michael, et al. "Cortisol on Circadian Rhythm and Its Effect on Cardiovascular System." International Journal of Environmental Research and Public Health 18, no. 2 (2021): 676. Accessed December 26, 2024. https://www.mdpi.com/1660-4601/18/2/676.
Clow, Angela, et al. "Cortisol Awakening Response: Regulation and Functional Significance." Endocrine Reviews. Advance article. Accessed December 27, 2024. https://academic.oup.com/edrv/advance-article/doi/10.1210/endrev/bnae024/7739741.