A study from the University of West England has led them to believe they’ve found the key to why women have scarier nightmares and are more likely to remember their dreams than men, London’s Daily Mail reported Thursday.

Psychologists said this may be due to changes in a woman’s body temperature caused by her period.

Dr. Jennie Parker, who led the study, recorded the dreams of 170 volunteers. Thirty percent of female students reported having nightmares compared to 19 percent of male students.

“Women who are premenstrual tend to dream more aggressively, and they are also more likely to remember the dreams,” Parker said.

Past studies have linked changes in body temperature with dreams. Researchers say women’s body temperature usually rises after ovulation — halfway through the monthly cycle — and falls again just before a period starts.

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