When Is The Best Time To Drink Coffee?

When Is The Best Time To Drink Coffee?

Caffeine is a stimulant of the central nervous system and it falls under the drug class of methylxanthines. The effects of caffeine are mediated via several different mechanisms:

  • • It inhibits and antagonises the A1 and A2a adenosine receptors
  • • It inhibits phosphodieserate
  • • It affects intracellular release of calcium
  • • It inhibits and antagonises different benzodiazepine receptors


Adenosine, just like melatonin builds up during the day and makes you sleepier in the evening. The adenosine builds up in the synapses between specific neurons in the brain, and this build up gradually makes you more tired in preparation for sleep.

What caffeine does is block those receptors and doesn’t allow adenosine to bind. It also has another physiological effect in that it increases cortisol levels.

Cortisol is the stress hormone, and although stress isn’t good for the body, it is this hormone that makes you alert and awake in the morning as the levels in your body escalate. As caffeine and cortisol have similar effects on the body, you want to drink your first cup of coffee when your natural cortisol levels are at their lowest. This way, you will feel the biggest impact.

During sleep, your cortisol levels are at their base line and at dawn they begin to rise with their peak levels around 1 hour after waking. The first dip of cortisol happens between 10am and 12pm - this is your coffee window, and when you should enjoy your first cup of coffee!

The caffeine will counter the cortisol dip by blocking some of the adenosine receptors, releasing cortisol and make you feel more awake again. If you drink coffee before this time window, you will find that caffeine does very little for you as your natural cortisol levels are so high.

Cortisol rises again during lunch and then dips again around 2pm to 4pm, so here would be another coffee window if you need an extra boost to power you through to the end of the day.


Circadian rhythms are natural, internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours. These rhythms are found in most living organisms, including animals, plants, and even some bacteria. The term "circadian" comes from the Latin words "circa" (meaning "around") and "diem" (meaning “day”.)

Circadian rhythms are crucial for regulating various physiological and behavioural processes, such as sleep, hormone production, body temperature, and metabolism. These rhythms are primarily influenced by external cues, most notably light and darkness.

The suprachiasmatic nucleus (SCN) in the brain's hypothalamus acts as the master clock, receiving signals from the eyes about light and darkness, and then coordinating the body's internal clocks accordingly. One significant factors that can influence these natural rhythms is our daily coffee consumption.

As you know, caffeine blocks the adenosine receptors in the brain, so drinking coffee too late in the day can interfere with the body’s ability to wind down, leading to difficulties falling asleep and reducing overall sleep quality. It’s crucial to note that the impact of coffee on circadian rhythm varies from person to person. Some people metabolise caffeine more slowly, making them more sensitive to its effects. Genetics, age and overall health also influence how our bodies respond to coffee consumption concerning circadian rhythms.

For those of you who are sensitive to caffeine, moderation is key, and being mindful of your coffee consumption in the latter half of the day can promote better sleep and overall health.

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