New year, new resolutions. For many, it may be a vow to live healthier and to give up what they consider a vice, like drinking too much coffee. It’s true that coffee is often the subject of conflicting studies ("It's good for you! Wait, no, it's bad!"). There is not a month in which a study is not published where the merits or defects of our favourite joe are not shouted out loud. According to some studies it extends life, according to others it is dangerous and so on and so forth.
You are not alone if you are unsure and confused by the academic research ping pong. Should you continue drinking coffee or should you give it up altogether? The truth lies somewhere in between: we can continue to consume it, but we must learn to do it the right way.
Coffee by itself (without cream and tons of sugar) has many intrinsic health benefits: it increases cognitive performance and helps concentration, improves short-term memory and the ability to make decisions. Coffee can thus easily be part of a healthy life. But - and there is a big but - coffee consumption has negative effects on our levels of cortisol, also known as the stress hormone.
So how do you get the benefits and avoid the side effects? There is a way: plan your coffee consumption throughout the day.
First thing first, to understand why coffee consumption should be regulated according to the times of day, we need to find out what cortisol is and how it works. Cortisol, also known as the stress hormone, triggers the "fight or flight" response in moments of fear, anxiety and danger. It activates a defence and warning mechanism that allows us to respond to threats, both real and imaginary, as swiftly as possible.
All good then; except when we produce too much of it. Our body produces optimal peaks of natural cortisol between 6 and 9 in the morning, it then fluctuates and goes down as we go into the evening. Without a consistent physical response, too much cortisol could cause weight gain, high blood pressure, severe mood swings, and irregular menstrual cycles.
We all love coffee especially for its stimulating effect. It helps us stay awake even when tiredness takes over. But it is precisely this stimulating effect that simulates a stressful event on our senses (accelerated heartbeat, heightened senses and so on) that causes a peak in cortisol.
Since the stress hormone already fluctuates by itself during the day, drinking a cup of coffee at the wrong time can bring disastrous effects.
For most people, their natural cortisol levels are already quite high in the early morning, so it would be a good idea to postpone your first cup of coffee after 10 am to avoid further spikes. So between 10 am and noon you can treat yourself to one or two cups of java, but the ideal time to really go for it is between 2 pm and 5 pm.
If you go to the gym after work for long and tiring workouts, then coffee is your ally. Between 4.30 pm and 5 pm cortisol levels continue to drop, so a sip of coffee or other caffeine-based drinks before performing sport can be useful. Indeed, studies actually show that controlled doses of caffeine may help improve weightlifting performance.
Caution: if you don't have the habit of drinking a lot of coffee, it is better to avoid consuming it at least 6 hours before going to sleep.
While it’s true that cortisol levels continue to drop between 7 pm and 10 pm, having coffee at this time of day could prevent you from getting a good night's sleep. Studies show that drinking coffee after a certain time at night can make you lose on average at least 2 hours of sleep. It’s therefore wise to completely avoid coffee consumption between 10 pm and 6 am, a period during which the stress hormone swells again.
In short, caffeine addicts need not quit coffee as their new year’s resolution; just set the alarm clocks and you’re set. Losing that holiday weight though, is a different story altogether…