If it sometimes happens that after a large cup of strong coffee in the morning you still yawning, you probably do something wrong.

The team from ASAP Science concluded that all who early staggered into the kitchen as zombies looking for a first cup of coffee – make a big mistake. Because it is not the right time for caffeine ‘shot’.

Our internal clock controls the release of cortisol (stress hormone) during the day, and is directly linked to the level of alertness. The level of cortisol peaks between eight and nine o’clock in the morning, which means that the body is trying to awake itself, whatever you drink coffee or not.

Scientists have found that drinking coffee in the early hours actually weakens the effect of caffeine, and develops resistance to it. In other words, at the moment when you prepare another ‘dose’ will need stronger or a larger amount of coffee to keep you awake.

In addition, you should avoid drinking coffee between noon and 13 hours, and 17: 30-18: 30, it means the time when you actually need to eat.

The body clock regulates sunlight and darkness, more than our sleep patterns. But even if we does not take this into consideration, usually cortisol levels automatically rises after we wake up, which means that if you are waking up in the winter during the night, you still might have to wait a bit before you get on to the first cup of coffee.