Washington: People who sleep longer are more at risk of developing Parkinson’s disease, according to a new US study.

Scientists at the National Institute of Health tracked the health of 80,000 fe,a;e nurses over a a 24 year period and discovered that those who sleep at least nine hours a night are almost twice as likely to develop Parkinson’s disease as those who get by on six hours or less. The study also showed that working night shifts may help prevent the disease.

All those tracked were free of Parkinson’s at the start of the study. They were asked about their sleep, smoking and dietary habits and weighed. By the end of the study, 181 had developed Parkinson’s.

The results which revealed a link between the length of sleep and a heightened risk of Parkinson’s are published in the American Journal of Epidemiology.

People who slept more than nine hours were more at risk and 80% more likely to have the condition than those who slept six hours or less. Sleeping eight hours equated to a 60 per cent chance of Parkinson’s and seven hours 10 per cent.
Sleeping longer and working night shifts reduced the risk.

Previous studies have shown that night-shift workers have lower levels of the hormones melatonin and oestradiol. At higher levels, they may contribute towards the development of Parkinson’s.

Lead researcher Dr Honglei Chen, admitted that the results were puzzling and that further research was required to examine the results.