New York, Dec 23 (IANS): A new study has linked physical violence against women by male partners to a disruption of a key steroid hormone that may trigger various negative health effects.

The study by University of Oregon and Oregon Social Learning Centre looked at daily fluctuations of cortisol (stress hormone) levels in men and women.

Cortisol was drawn from saliva samples of 122 couples during on-site assessments and four times a day over four consecutive days.

Cortisol levels typically rise as people wake up, peak shortly thereafter and then decline rapidly.

Researchers compared the cortisol levels with the frequency of interpersonal violence as reported by both partners in the relationships.

The team noted a disruption from normal daily cortisol rhythms only in women as seen by a slower decline through the afternoons and higher-than-normal levels late in the day.

"We found that women's, but not men's, victimisation was associated with multiple indicators of daily cortisol levels," said the study's lead author Hyoun K Kim, a scientist at University of Oregon's social learning centre.

The findings show a correlation between violence and cortisol levels in women.

However, the authors do not rule out the possibility that abnormal cortisol cycling may contribute to interpersonal violence.

The research appeared in the journal Psychoneuroendocrinology.