A study this month showed that sleeping more at weekends could raise the risk of diabetes and heart disease. So, should you really get up on a Sunday?
Could your weekend lie-in kill you? asked the Daily Mail last week. It cited a study in this month’s Journal of Clinical Endocrinology and Metabolism (JCEM) that links sleeping more at weekends with an increased risk of diabetes and heart disease. Since most of us change our sleep schedule depending on whether it’s a work or non-work day, it’s an interesting question. Is lying-in really so dangerous? Researchers say that changing sleep patterns causes social jet lag. Is that even a thing?
Shifting our sleeping hours by a few hours has the effect of crossing a time zone – it throws out our circadian rhythms and makes us sleepy during the day. It also – according to JCEM’s study, of 447 people who were monitored with a wrist accelerometer for a week – increases levels of triglycerides and lowers levels of the “good” type of cholesterol. People who shifted their sleep patterns were also more likely to gain weight during the study. Those with an evening chronotype – meaning their biological clock is more suited to going to bed and waking later – were more at risk of these changes than earlier sleepers and risers. So should you set your alarm at the weekends?
This study shows an association between shifting sleep patterns and changes in some blood results. It does not show that anyone developed heart disease or diabetes because they had lie-ins. It also does not show a relationship between dose and response – so it is unclear how much of a sleep shift you would need in order to cause the changes seen in the blood-test results. The concept of social jet lag is likely to feed our anxiety about sleep and how we do not get enough of it. Emeritus professor Jim Home, of the Sleep Research Centre at Loughborough University, says we should really stop worrying so much. Worry is bad for sleep and we naturally compensate for not getting enough rest in the week by lying-in at weekends, so we shouldn’t stop doing it.
Home says studies show that if you accumulate a five-hour sleep debt during the week (a typical amount), then you only need one and a half hours of extra sleep on your days off to make up for it. It would be a shame to be scared of a lie-in. Studies of sleep and risk factors for heart disease and diabetes can struggle to differentiate between poor sleep causing stress and stress disrupting sleep. Work stress can cause both a rise in blood pressure and changes in sleep patterns. Sleep is the litmus test for the state of one’s health, and the most important thing that happens when you don’t get enough of it is that you feel sleepy – which could be more of an immediate health hazard than a raised triglyceride level.
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