"At the moment 80 percent of the population is forced into a work timetable which is not suited to them."

London – Employers should allow staff to have a lie in if it suits their body clock, biologists suggest.

Reorganising the day to let people work according to their individual ‘chronotype’, will make them happier and healthier, according to a new study.

Every person has a slightly different body clock or chronotype, putting them each on a spectrum between the ‘morning lark’ who likes to be up at dawn, and the night owl who prefers to work into the evening.

But four out of every five people are working against their individual body clock, scientists suggest - forced by the dictates of society and employment to be active when they should be asleep

This problem, which biologists call ‘social jetlag’, has been linked to diseases such as diabetes, obesity and cancer.

Now, in an experiment in a German steel factory, scientists have demonstrated that allowing people to adjust their work pattern to suit their individual preferences results in a much happier, healthier workforce.

The researchers, from the Institute of Medical Psychology at Ludwig-Maximilian-University in Munich, first assessed the chronotypes of 114 steel workers, examining their sleeping patterns and calculating their average sleep deficit.

Each worker was put into an early, late, or intermediate group, and assigned a shift pattern to suit their body clock.

The biologists then monitored their sleep, stress levels, happiness and general wellbeing over five months.

The results, published in the journal Current Biology, showed an improvement in all areas.

Professor Till Roenneberg, who led the study, said: ‘A simple re-organisation of shifts according to chronotype allowed workers to sleep more on workday nights.

‘As a consequence, they were also able to sleep less on their free days due to a decreased need for compensating an accumulating sleep loss. This is a double-win situation. We know that people who sleep better perform better, however you measure it.

‘Their health improves, they take fewer sick days - these are goals which all employers are interested in.’

Nearly all living things have an internal mechanism - known as the circadian rhythm - which synchronises bodily functions to the 24-hour pattern of the Earth’s rotation.

In humans and other mammals, the clock is regulated by the bodily senses, most importantly the way the eye perceives light and dark and the way skin feels temperature changes. The mechanism rules our daily rhythms, including our sleep and waking patterns and metabolism. It also determines if we are a ‘morning’ person or an ‘evening’ person.

But the pressures of modern living mean we are now increasingly working against our clocks and risking long term health problems from metabolic disease.

Professor Roenneberg suggested that employers should offer staff the chance to have their body clock independently assessed, and then be given the option to work according to their own pattern.

‘This won’t suit everyone,’ he said. ‘Many people, for example, have to look after children.

‘We have to take these things into consideration and people should not be forced to work according to these patterns.

‘But at the moment 80 percent of the population is forced into a work timetable which is not suited to them.’

Céline Vetter, co-author of the study, added: ‘We know that sleep has important implications not only on physical health but also on mood, stress, and social interactions, so that improving sleep will most probably result in many other positive side effects.’

The research comes after Professor Vincent Walsh, an expert in brain research at University College London, proposed last year that that workers should be allowed an afternoon nap at work to boost productivity.

‘It’s only since the industrial revolution we have been obsessed with squeezing all our sleep into the night rather than having one or two sleeps through the day,’ he said.

The professor said a nap of between 30 and 90 minutes in the afternoon could help companies improve productivity.

‘If we want people to be more creative we need people to be able to do less. Companies should allow naps in the afternoon. They should get rid of the habit of clocking in and clocking out.’

Daily Mail