In the early afternoon, I often catch myself listlessly staring into the computer screen. I have things to do, but I can’t concentrate. I try writing the same sentence five times and delete it six. During one of these afternoon torpors, I came upon a word: acedia. It seemed to perfectly define my mid-afternoon weariness. I discovered this originally Greek word was widely used by medieval Christian monks to describe a sense of indolence, a mood of lethargy, a feeling of being completely unconcerned about their duties and purpose in the world. Christian mystics who lived in the Egyptian deserts during the 3rd century AD often complained about being haunted by the “noon-day demon”.

One monk of the time described how the noon-day demon would “make the sun appear sluggish and immobile” and cause “monks to continually look at the window and forces him to gaze at the sun”. This cruel demon “sends him hatred against the place, against life itself, and against the work of his hands, and makes him think he has lost the love among his brethren and there is none to comfort him”.

To escape my own noon-day demon, I continued my research. I discovered acedia spread from the Desert Fathers into the monasteries of medieval Europe, where it was seen as a sin that monks needed to overcome.

Some think that acedia faded with medieval Christian monastic life and was replaced with more recognisable terms such as boredom. However, others think acedia continued to live on. For instance, Aldous Huxley argued that acedia had only intensified with the onset of modern life. More recently, the psychoanalyst Josh Cohen identifies how a certain torpor or aimlessness he noticed in some of his clients seems to be a typical response to our culture of over-achievement and overwork.

The question about how to address this malaise has piqued the interest of sleep researchers, who have focused on our body’s circadian rhythms. They have found that during the early afternoon, people’s internal body clock tends to cycle downwards. Our internal temperature changes and we start feeling more sleepy. The downward tendency of our internal rhythm in the middle of the day is also linked with a dulling in the part of brain that is linked with reward-seeking activities. This region – the left putamen – tends to be more active at 10am and 7pm rather than 2pm.

The midday lethargy is made much worse by chronic lack of sleep among significant parts of the population. According to one survey, one-third of Britons say they get five to six hours sleep a night. Another UK survey found that 30% of respondents were severely sleep deprived. Not having enough sleep can make it harder to make decisions – particularly in novel or high-pressure situations. It also make us worse at performing tasks – particularly those involving an emotional component. A lack of sleep makes us less able to recognise emotions such as anger and happiness in others. At the same time, it also makes us more likely to feel stressed, anxious and angry.

Behaviourial scientists suggest a range of lifestyle hacks to deal with the noon-day demon. They include physical movement, meditation, listening to upbeat music and avoiding the temptation of an afternoon sugar and caffeine hit.

Others think a few life-hacks aren’t enough, and instead we need to change the way work is designed. Workplaces could provide more scope for flexible working to accommodate people’s natural rhythms or firms could encourage “strategic napping”. They might also help employees manage their boundaries between work and life.

Changing habits and altering some aspects of the working day might help to deal with fleeting feelings of listlessness among employees. But these interventions are unlikely to address the deeper, more grinding sense of emptiness some employees feel at work. Tackling this involves asking questions about how to make our work more meaningful. That doesn’t mean pep talks from top management about how you are helping to save the world – those kind of overblown motivational speeches are often completely ineffective. What might cut through is creating a sense of “local meaning” around your work. That can be achieved by having a sense of who benefits from what you do, being recognised for doing a good job, having an answer to why your work is important and feeling connected to your colleagues.

Feeling like our work is more meaningful is important, but it might not be enough. There’s a strong case that when we are struck with acedia or simply mid-afternoon sleepiness, we should just give in, pack up, go home and start again fresh tomorrow. Stopping work in the early afternoon might not be such a bad thing – after all, there is an increasingly strong case that a shorter working day decluttered with distractions is likely to make us more productive.

Finally, day workers like me should remember their life is easy when compared to those who work at night. People who often do some of the most important jobs – such as nurses and doctors – have shift patterns that mean they get much less sleep and suffer more ill health than day workers. Battling the noon-day demon is nothing when compared with the midnight spectre that haunts some people.

• André Spicer is professor of organisational behaviour at the Cass Business School at City, University of London