There is a moment, deep in the afternoon - just as your lunch is settling - that the human mind lulls. It creeps up on you. You try to shake it off, but it clings on. Sorry, friend, your brain says the lull is coming whether you like it or not.

Teachers, of course, do not like it. They have 30 pupils staring at them, demanding things, wanting to be taught. A lull is not helpful. A lull is a lesson ruiner.

And many teachers have said the lull has got worse during the period in which they have been working from home. Without the adrenaline rush of a classroom, it has everything its own way.

But is the lull inevitable? Can a teacher actually sustain their mental capabilities and teaching abilities across a typical six-hour day with only short breaks? What does science have to say about this?

Let’s look at attention first. Attention is the idea that we have limited capacity for information processing and thus must selectively focus our cognitive resources. In a lull, it certainly feels as if our attentional resources have disappeared. But is that true?

“What research has shown is that it is harder to sustain attention when the task is very boring, monotonous and repetitive,” says Nilli Lavie, leader of the Attention and Cognitive Control Group in UCL’s Institute of Cognitive Neuroscience.

Does that mean that if a teacher does not manage to keep their attention during a lull, it is because the lesson that they are teaching is a boring one?

Not quite. The description above is “not the case for a teacher’s job,” says Lavie (who is a professor of psychology and brain sciences, so don’t argue). And that makes intuitive sense: how could a job as diverse as teaching ever be said to be boring?

So, what else is going on, then?

Ability to concentrate works on a spectrum. Some individuals may be more susceptible to distraction, while still being well short of the clinical concentration difficulties we see in behavioural disorders such as ADHD.

“Everyone - teachers, journalists, anyone - would be somewhere on the spectrum,” says Lavie, a professor of psychology and brain sciences (did I mention that already?).

In fact, attention distractibility is akin to a personality trait and stems from differences in brain structures, she adds. Those with “smaller brain volume, in particular, frontal cortex areas are less able of exerting what we call cognitive control and paying attention to what they are meant to be paying attention to.”

So, after a morning of teaching, some of us may be more susceptible to a mid-afternoon mind wander than others. Is there anything those of us more at risk can do about that?

Alejandro Lleras, a psychology professor at the University of Illinois, has looked at the kind of break periods that can help individuals try to maintain attention over the course of a day, highlighting activities that are easily started and that are the most effective.

He also highlights what is not effective: getting too caught up in your breaktime activity. This “probably means [doing] activities that are not overly emotional,” says Lleras. “It would not be ideal to use a brief break to call your spouse and try to finish a disagreement or altercation,” he adds (don’t pretend you’ve never done it).

So, what does work? Having a conversation and simply doing nothing count - just as long as you are not talking, or thinking about, what you were doing before. If you do this, you are “dual tasking”, which is “really detrimental to performance”, Lleras advises.

So, having a staffroom conversation with colleagues about the class you just taught would not be a proper break. And finishing a disagreement or altercation with a colleague about your work would be trampling all over the guidance several times.

Staring aimlessly out of the window thinking about dinner? Chatting about Love Island? Mindfully eating your sandwiches? All good.

So, that’s attention - it can play a role in any drop in performance during the afternoons, but it is not the only factor at play. Just as important, say researchers, is how the school day is structured.

There is plenty of research suggesting that pupils’ circadian rhythms, or body clocks, impact their learning and should be taken into account when scheduling the school day. The US state of California has introduced a law that means middle schools will start their classes at 8am or later, while high schools will start no earlier than 8.30am (some schools in the state were previously requiring students to be in class before 7.30am). The state senator who introduced the legislation cited as evidence a 2014 policy statement from the American Academy of Pediatrics, which called early school start times a “key modifiable contributor to insufficient sleep, as well as circadian rhythm disruption” among teenagers.

But such issues are also a huge problem for teachers, according to Paul Kelley, co-author of Body Clocks: the biology of time for sleep, education and work, a former secondary school headteacher whose research has focused on resolving the discrepancy between our “genetically created circadian time” and society’s clock time.

There haven’t been any studies of the impact of the misalignment between circadian rhythms and teaching performance - but Kelley, honorary associate in sleep, circadian and memory neuroscience at the Open University, makes some extrapolations from his research in light of his own school experience.

One four-year study, on which he was lead author, found that introducing a 10am start time for 13- to 16-year-olds at a UK secondary school led to a 50 per cent decrease in student illness and “was associated with a 12 per cent increase in the value-added number of students making good academic progress”.

He explains that teachers face an “impossible job” because the pupils they are working with - around 30 of them in a class, most likely - “are on a different time schedule on average” to their teacher. Just as the students approach their peak, the teacher is tiring. So, as that natural lull hits teachers, pupils are at their most lively.

It’s well known among teachers that students tend to be more difficult in the afternoon, which is precisely when adults will, conversely, be running out of steam. This means older teachers, in particular, “can’t make it through a school day at their best”, according to Kelley.

In his argument, schools are starting too early and the working school day is too long. “On average, it’s a stupid system at the wrong time,” he says.

What’s more, Kelley argues, it’s a system that could be creating “huge health problems” for teachers.

He highlights research that has shown the health impact on shift workers who consistently work out of sync with circadian rhythms - an arrangement that also creates “performance problems”. Teachers “have this time pressure, which is unremitting and not obvious”, he adds.

Given the fundamental misalignment between teacher and pupil body clocks, Kelley believes there is no perfect solution. But the school start time is at present “about two hours earlier than it should be” and making that switch would be the best option to hit the middle ground between the pupil and teacher circadian rhythms.

That raises some big questions, though: could such a shift be made to work for teachers with their own young children? And would it still work for parents who need to drop off their children at school early?

All this reflects a fundamental point about teachers’ ability to sustain attention and cognitive focus - unlike other professions, they are working with much younger people whose capacities on that front may be very different to their own.

Lavie (for those with smaller frontal cortexes, she is the UCL specialist in attention) thinks that her field pinpoints a key issue for teachers in showing that attention distractibility is like a personality trait. “It’s quite important to recognise that not everything is about motivation or discipline,” and that attention distractibility can be beyond “voluntary control” for pupils, she adds.

Combine this with the different body clocks of teachers and pupils and it becomes clear that we need to pay more attention to attention - to keep watch on our body clocks, and on the ways we might improve the situation in the classroom for everyone.

Now, if you have managed to maintain focus until this point, take a break.

John Morgan is a freelance journalist

This article originally appeared in the 31 July 2020 issue under the headline “Tes focus on…Beating the afternoon lull”