By Victoria Allen Science Correspondent For The Daily Mail
Published: 17:08 GMT, 1 March 2019 | Updated: 17:13 GMT, 1 March 2019
Women who work night shifts may risk going through the menopause at a younger age.
Even occasional night shift workers are nine per cent more likely to have an early menopause, a study has found.
This matters because women who go through the menopause younger are at greater risk of cardiovascular disease, osteoporosis and may even suffer memory problems.
Women who work night shifts may go through the menopause at a younger age (stock)
Researchers tracked more than 80,000 nurses who worked night shifts over 22 years.
The risk of early menopause was found in those who worked almost two years of night shifts.
Women who disrupt their body clocks by staying up at night have lower levels of the sleep-hormone melatonin, which some experts believe is important for the ovaries.
But it may also be the stress and tiredness of night-working which disrupt oestrogen levels and plunge women into menopause at an early age.
Dr David Stock, who led the study from the University of Dalhousie in Canada, said: 'This is the first study into a link between rotating night shifts and age at menopause, and we found a moderate but significant link.
'For women who went through the menopause before the age of 45, shift work seemed to be particularly important.
'This could be due to disruption of their circadian rhythms, stress or fatigue, although more research is needed.'
Women who work night shifts have a greater risk of breast and endometrial cancer, previous studies have found.
Menopause is defined as the changes a