It may seem that a cup of strong coffee first thing in the morning is the best way to get yourself going, but in fact waiting until later may be better.
Scientists have worked out that the best time to get a daily hit of caffeine is on average between 9.30am and 11.30am.
This is due to the way caffeine interacts with a key hormone – called cortisol – which helps to regulate the body’s own internal clock and promotes alertness.
Cortisol levels are naturally high shortly after waking up and can remain high for up to an hour afterwards – with the average peak being between 8am and 9am.
Steven Miller, a neuroscientist at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, argues it is better to then drink caffeine after this peak as it promotes cortisol production.
He said that drinking coffee while levels of this hormone are high can cause people to develop a tolerance of the caffeine it contains, meaning they often need an extra shot in their morning cup to get the same effect.
Writing as part of a light-hearted look at the evidence on his blog, he said: “If we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it.
“This is because cortisol production is strongly related to your level of alertness and cortisol peaks for your 24 hour rhythm between 8 and 9am on average
“One of the key principles of pharmacology is use a drug when it is needed. Otherwise, we can develop tolerance to a drug administered at the same dose.
“In other words, the same cup of morning coffee will become less effective and this is probably why I need a shot of espresso in mine now.”
Mr Miller, a neuroscience PhD student, wrote the advice after examining the evidence for how cortisol changes through the day.