When is the best time to drink coffee?

There is something romantic about brewing a carafe, or holding a freshly bought cup close, first thing. Photo / Thinkstock

Coffee has ingrained itself in the mechanisms of so many people's early morning routines. There is something romantic about brewing a carafe, or holding a freshly bought cup close, first thing.

There is also something practical about it - sipping piping hot caffeine as soon as possible prepares us for the day or, at the very least, for the coming few hours.

But drinking coffee shortly after waking up, it turns out, is actually a bit counterproductive. Not only does it undermine the caffeine's effect, but it tends to lead people to build a tolerance for the drug, thereby diminishing its effect down the road.

Our bodies produce a hormone called cortisol, which has been branded the "stress hormone", because it tends to appear when we are either stressed or fearful. But that same hormone is also a key component of our natural, day-long hormonal cycle, known as the circadian clock, which helps wake us up in the morning and wind us down at night.

The gist is that when our body releases cortisol, we feel more awake.

There are two basic problems with consuming caffeine when cortisol production is high. First, caffeine tends to interfere with the production of cortisol. The body then produces less of the hormone and relies more on the caffeine.

Second, drinking coffee while cortisol is high leads us to develop long-term tolerances for caffeine, which is why so many habitual coffee drinkers say it has less of an effect on them. Caffeine replaces the boost we would ordinarily get from cortisol rather than supplementing it.

Three times throughout the day - in the early morning, around midday, and in the evening - cortisol levels rise. It is highest between 6am and 10am (particularly so between 8am and 9am).

It is during the troughs - between roughly 10am and noon, and 2pm and 5pm - when people should drink coffee if they want to get the most out of their caffeine.

Coffee drinkers who are exhausted in the morning without their coffee are likely to have altered their circadian rhythm in such a way that they need the caffeine boost in order to reach the level of wakefulness they used to achieve without it.