The factor that may increase teens’ risk of MS by 50%

Teenagers who sleep poorly – less than seven hours a night – are between 40% and 50% more likely to go on to develop multiple sclerosis (MS) later on than those who have good sleep, a recent population-based study from Sweden has found.

The time differences the sleep took place in due to school or weekends didn’t affect this risk.

Research has investigated the affect of shift work, and particularly at a young age, and found it raises the risk of MS. It’s also known that poor sleep quality stimulates pro-inflammatory pathways and it’s thought this can increase the risk of inflammatory diseases.

Poor sleep quality and duration had, however, not been thoroughly examined.

To investigate, Swedish researchers used data from the Epidemiological Investigation of Multiple Sclerosis which was launched in 2004 and features people aged 16-70 from the general population of Sweden.

Overall the results showed that people who slept less than seven hours a night in adolescence were 40% more likely to get MS in later life, compared to people who slept for seven to nine hours. Those who slept longer at weekends but still less than seven on a weekday (or work day) still had a 30% increased likelihood.

The association remained after researchers adjusted for other risk factors like smoking, body fat and Epstein-Barr virus infection. Other conditions at the age of 20 and at the onset of MS did not affect the findings, neither did the mean weekly sleep duration.

The study then looked at sleep quality. Those with low quality in adolescence were 50% more likely to develop MS than people who reported good to very good sleep. This association was still significant whether people slept for more or less than seven hours.

The researchers said that the findings should be interpreted with cautious because it’s not known if reverse causation was at play – poor sleep might be because of, and not a cause of, MS that was as yet undetected. Other studies have found that sleep disorders may begin years before the onset of more widely recognised MS symptoms.