Divorce is not only upsetting and expensive, it could also lead to premature death.

Those who lose sleep worrying over their separation show increased blood pressure, a study has found.

A growing body of research links divorce to serious negative health effects and even early death, yet few studies have looked at why that connection may exist.

Divorce-related sleep troubles may be partly to blame, scientists suggest.

Dr David Sbarra, of the University of Arizona in the U.S., said: 'In the initial few months after a separation, sleep problems are probably pretty normal, and this is an adjustment process that people can typically cope with well.

'But sleep problems that persist for an extended period may mean something different.

'It may mean that people are potentially becoming depressed, that they're struggling with getting their life going again, and it is these people that are particularly susceptible to health problems.'

The research analysed 138 people who had physically separated from or divorced their partner about 16 weeks before the start of the study. The participants were asked to report on their quality of sleep during three lab visits over a seven-and-a-half-month period. Their blood pressure was also measured at each visit.

Researchers saw a delayed effect, with people showing increased systolic and diastolic blood pressure in later visits to the lab as a result of earlier sleep problems.

The systolic reading measures the pressure in the arteries when the heart beats, while the diastolic reading measures the pressure in the arteries between heartbeats. Normal blood pressure is around 120/80.

Dr Sbarra said: 'We saw changes in resting blood pressure were associated with sleep problems three months earlier. Earlier sleep problems predicted increases in resting blood pressure over time.'

The researchers also found that the longer peoples' sleep problems persisted after their separation, the more likely those problems were to have an adverse effect on blood pressure.

Dr Sbarra said: 'What we found was if you're having sleep problems up to about 10 weeks after your separation, they don't appear to be associated with your future increase in blood pressure.

'However, after 10 or so weeks - after some sustained period of time - there seems to be a cumulative bad effect.'

He said for people who have high blood pressure to begin with, the increase is not to be taken lightly, adding that each increase in sleep complaints corresponded to a roughly six unit increase in subsequent systolic blood pressure.

For people who start at the high average range, this increase is far from trivial, he added.

Lead study author Kendra Krietsh suggests that people who have persistent difficulties sleeping after a divorce should seek cognitive behavioural therapy, make daily schedule adjustments that promote healthy sleep, or find new ways to relax at bedtime.

She added: 'If somebody is going through a divorce and unable to sleep, they really need to get some help or it could lead to problems. We are all going to go through something stressful in our lives, whether it's a divorce or something else, and this shows how important it is for all of us to value sleep and take care of ourselves.'