People who stay up late and struggle to wake up are more likely to die prematurely than early risers, according to a study of nearly 433,000 people. The research found that night owls had a 10 per cent higher risk of early death compared with morning larks, after adjusting for factors such as age, sex, smoking and socioeconomic status.
The study, published in the journal Chronobiology International, asked participants aged 38 to 73 to classify themselves as definite morning, moderate morning, moderate evening or definite evening types. Over a follow-up period of up to six and a half years, the chance of death was lowest among definite morning types and increased progressively with later body clock types.
Evening types were also 90 per cent more likely to have psychological disorders and 30 per cent more likely to have diabetes, as well as being more prone to gastrointestinal and neurological conditions. The authors did not establish causation but suggested that the health harms may stem from night owls having to adapt to a 'morning lark world'.
Professor Malcolm von Schantz of the University of Surrey, a co-author, described the issue as a public health problem that can no longer be ignored. He called for allowing evening types to start and finish work later where practical, and for more research into helping them synchronise their body clocks with sun time.
However, the researchers stressed that night owls are not doomed. Between 40 and 70 per cent of a person's circadian rhythm is genetic, with the rest influenced by environment and age. Tips to shift the body clock earlier include exposure to morning light, maintaining a regular bedtime, and adopting healthy lifestyle behaviours.
