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In John Medina’s great book “Brain Rules” he discusses the two basic chronological types we fall into. Are you a “lark” or an “owl”?
Larks are the early birds, bright in the morning, raring to get things done. Their peak performance thinking time lasts up until lunchtime.

Owls, by contrast, have to fight to get going in the morning, consume vats of coffee to stimulate their brains into action but start to light up later in the afternoon.

Knowing when your optimum thinking time is one thing. How to slot that into your daily work can be a different matter altogether. Shift workers have an even greater challenge of having to continually work against their natural body clock and it comes with a cognitive and health cost.

Disrupting our natural body clocks has been shown to enhance ageing, impair our immune system and increase our risk of obesity and diabetes. It has even been linked to an increased risk of neuro-degeneration, loss of motor function and premature death.

Having formerly having to work nights as a nurse and then as a junior doctor, I am only too cognisant of the deleterious effect that sleep deprivation has on my own thinking skills. Even simple mathematical calculations to work out fluid balance sheets become tortuous and often full of errors.

But if you are not an owl, or a lark, or a shift worker, do you need to put any thought into what you do when during the day? The simple answer is yes. Many studies have now revealed that the timing of what we choose to do in our working day can have a huge impact on our productivity and efficiency.

If you are a morning person, then scheduling appointments and meetings would be better suited for you in the afternoon to keep our working memory freed up for higher thinking items. If you are an afternoon/evening person then the converse applies.

But what about other types of thinking – the thinking that requires insight and creativity? Are you better off doing that type of brainwork at your optimal thinking time as well?

A study by Wieth published in “Thinking and Reasoning” in 2011 found that you are more likely to have more insights into your non-optimal thinking time. This is because to have one of those lovely “Aha” moments, your brain has to be defocussed to allow the brain to quieten down. So actually when you are tired and perhaps not terribly attentive, is the best time for to come up with the answer to that curly question you had been pondering on before.

Of course, paying attention to hunger and the food we eat also makes a difference. Hunger itself can be a distraction. But loading up on carbs in the middle of the day with pasta or focaccia can also lead to post prandial sleepiness – which is not so great is you have a busy afternoon. Here promoting brainpower can be more readily achieved with some lean protein, fruit and veggies and perhaps a little carbohydrate.

Unless of course, you are going to follow the lifestyle habits of the Spanish, Italians and Greeks. We can learn a great deal from those who live around the Mediterranean where the daily “siesta” remains a way of life.

Having a break from work after a busy morning is a great way to give your brain a “brain break” so it can evaluate, reflect and determine which pieces of information need to be considered for long-term storage in our memory. Having a siesta helps to encode of memory. You remember far more by sleeping after learning. Then, after a couple hours of rest when your brain has done its sorting work, you are cognitively re-charged for the remainder of the day.

NASA has revealed that a short power nap of just 30 minutes can boost cognitive performance. I wonder how much more work we would all get done and get done well if we all had a regular afternoon nap?


Medina, J. (2009) Brain Rules: 12 principles for surviving and thriving at work. Home and school. Seattle: First Pear Press.

Mareike B. Wieth & Rose T. Zacks (2011): Time of day effects on problem solving: When the non-optimal is optimal, Thinking & Reasoning, 17, 387-401

Krishnan N,  et al.(2012) Loss of circadian clock accelerates aging in neurodegeneration-prone mutants. Neurobiol Dis. 2012 Mar;45(3):1129-35. Epub 2011 Dec 27.

Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, keynote speaker and best-selling author. You can now pre-order her new book ‘The Natural Advantage’ due for publication in October 2024.

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