Those who experience persistent sleep problems after a divorce stand to suffer from more than just dark circles. They might also be at risk for potentially harmful increases in blood pressure, a new study finds.

A growing body of research links divorce to significant 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, suggest the authors of a new study to be published in a forthcoming issue of the journal Health Psychology.

"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," said UA associate professor of psychology David Sbarra, who co-authored the paper with two of his former students - lead author Kendra Krietsh and Ashley Mason.

"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," Sbarra said.

The study looked at 138 people who had physically separated from or divorced their partner about 16 weeks before the start of the study.

Participants were asked to report on their quality of sleep during three lab visits over a seven-and-a-half-month period, using the Pittsburgh Sleep Quality Index, which takes into consideration sleep issues ranging from tossing and turning to snoring to difficulty falling and staying asleep. Participants' blood pressure also was measured at each of the three lab visits.

Although researchers did not observe a relationship between sleep complaints and blood pressure levels at the participants' first lab visits, they did observe a delayed effect, with participants showing increased systolic and diastolic blood pressure in later visits as a function of earlier sleep problems.

"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," Sbarra said.

In addition, the researchers 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.

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

For people who have high blood pressure to begin with, the increase is not to be taken lightly, Sbarra noted.

"Each standard deviation increase in sleep complaints corresponded to a roughly six unit increase in subsequent systolic blood pressure," Sbarra said. "If you're starting at the high average or low hypertensive range, this is a nontrivial bump."

Systolic is the top blood pressure number and measures the pressure in the arteries when the heart beats; diastolic is the bottom number and measures the pressure in the arteries between heartbeats. Normal blood pressure is around 120/80.

Lead study author Krietsh - who began exploring the link between divorce, sleep and blood pressure as part of her honors thesis as a UA undergraduate - suggests that people who have persistent difficulties sleeping after a divorce address the issue by seeking out cognitive behavioral therapy, making daily schedule adjustments that promote healthy sleep, or finding new ways to relax at bedtime.

"If somebody is going through a divorce and unable to sleep, they really need to get some help or it could lead to problems," said Krietsh, who earned her bachelor's degree in psychology from the UA in 2012 and is now pursuing her doctorate in clinical psychology at the University of Florida.

"We are all going to go through something stressful in our lives, whether it's a divorce or something else, Krietsh said, "and this shows how important it is for all of to value sleep and take care of ourselves."