My cognitive peak

According to my new fitness tracker, last night I slept for 7 hours and 47 minutes, of which 2 hours and 7 minutes were REM sleep. I ran 3 miles this morning before breakfast and I had my second coffee of the day twenty minutes ago. Right now, I feel like I am at my cognitive peak. But am I?

We know that the brain is a dynamic organ that changes over time, as we age, learn new things and practice particular skills. The sum effect of these different processes is that for any given brain function, there is a characteristic age at which this process is at its peak.

Using data from more than 48,000 participants, researchers in Boston recently characterized this for a range of cognitive functions. They found that tests reliant on short term memory tended to peak early, during teenage years. For tests more reliant on experience, such as measures of vocabulary, reading comprehension, and general knowledge, people performed best at around 50 years old.

Day by day, we are not always aware of those long-term changes. However we often notice short term effects on cognition: feeling frazzled at the end of a long meeting, mentally slow the morning after a big night out, or unable to concentrate when we haven’t eaten for a long time. Up until now, the technology available to routinely measure these changes has been cumbersome, so detailed data showing within-day cognitive changes have been rare.

We do know however that these within-day fluctuations can have serious consequences. One of my favourite real-world studies of recent years is a study of the decisions made by experienced judges working on a parole board in Israel. The first prisoner who came up for parole each day had about a 65% chance of being freed — but for the last prisoner seen before a refreshment break that chance was close to zero.

What applies to judges almost certainly applies to the rest of us too. While many safety-critical professions schedule in mandatory rest and refreshment breaks, the rest of us often squeeze in one last piece of important work before leaving for home — when we’re tired, hungry, and cognitively-suboptimal.

That’s it, I’m off for another cup of coffee.

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