Night owls – people who like to go to bed late and get up late – have a 10 per cent higher risk of dying than early birds, a study found.
Research based on 50,000 people in the UK found they had the higher chance of death over the six-and-a-half year period they were being studied.
It seems that living in a world geared to early risers damages the health of those who prefer moonlight.
And the switch to British Summer Time – pushing the clocks an hour forward in the Spring – makes things even worse for late risers, the scientists said.
Kristen Knutson, associate professor of neurology at Northwestern University Feinberg School of Medicine said: ‘Night owls trying to live in a morning lark world may have health consequences for their bodies.’
Previous studies have found that staying up late has bad effects on the heart and metabolism.
But night owls still had a 10 per cent higher risk of death after the effects of health were adjusted for.
Malcolm von Schantz, Professor of Chronobiology at the University of Surrey, said: ‘This is a public health issue that can no longer be ignored.
‘We should discuss allowing evening types to start and finish work later, where practical.
‘And we need more research about how we can help evening types cope with the higher effort of keeping their body clock in synchrony with sun time.
‘It could be that people who are up late have an internal biological clock that doesn’t match their external environment.
‘It could be psychological stress, eating at the wrong time for their body, not exercising enough, not sleeping enough, being awake at night by yourself, maybe drug or alcohol use.
‘There are a whole variety of unhealthy behaviours related to being up late in the dark by yourself.’
The researchers asked 433,268 participants, age 38 to 73 years, if they are a ‘definite morning type’ a ‘moderate morning type’ a ‘moderate evening type’ or a ‘definite evening type’.
Deaths in the sample were tracked up to six and half years later – and then it was calculated what type of person was most likely to die.
Professor Knutson said that we are not ‘doomed’ by our biology as even if we are a definite night owl or early bird, there are things that we can change to benefit our health, such as getting more flexibile working hours.
Professor Knutson said: ‘If we can recognize these chronotypes are, in part, genetically determined and not just a character flaw, jobs and work hours could have more flexibility for owls.
‘They shouldn’t be forced to get up for an 8am shift. Make work shifts match peoples’ chronotypes. Some people may be better suited to night shifts.’
The researchers’ next project is to see if night owls are able to shift their body clocks to adapt to an earlier schedule – to see if there are improvements in blood pressure and overall heatlh.
The switch to daylight savings or summer time is already known to be much more difficult for evening types than for morning types.
Professor von Schantz said pushing the clocks forward in countries that adopt daylight saving time – such as British Summer Time – has negative health effects.
He said: ‘There are already reports of higher incidence of heart attacks following the switch to summer time.
‘And we have to remember that even a small additional risk is multiplied by more than 1.3 billion people who experience this shift every year.
‘I think we need to seriously consider whether the suggested benefits outweigh these risks.’
