Sex may reduce stress, study shows

The research, conducted on rats, found that sex also stimulates cell growth in the hippocampus, a region of the brain that plays a key role in spatial navigation and long-term memory.

Previous research had shown that unpleasant, stressful experiences increase anxiety and can stifle cell growth in the hippocampus, which is also associated with anxiety regulation. To investigate whether rewarding but stressful experiences had similar effects, three Neuroscience Institute researchers — Benedetta Leuner, Erica Glasper and psychology professor Elizabeth Gould — studied the effect of sex on hippocampal structure and function in adult rats.

In the study, published in the Public Library of Science journal in July, the researchers tested three groups of adult male rats for 14 days. The first group was introduced to sexually receptive female rats once during the experiment, the second group was introduced to sexually receptive females once daily, and the third group was exposed to sexually unreceptive females.

Both groups of sexually active rodents were less anxious than the rats that had had no sexual experience. The researchers tested anxiety levels through an experiment in which rats were allowed to consume food in a novel environment, with shorter delays indicating less anxiety.

When compared to the sexually inactive group, both groups of sexually active rats also showed an increase in the number of neurons in the hippocampus. The rats that had chronic sexual experiences also showed growth in adult brain cells.

Both sexually active groups showed a post-intercourse jump in corticosterone levels, which are associated with higher stress, following their first sexual act. The chronically sexually active group no longer experienced the jolt of corticosterone after later instances of intercourse, but did demonstrate more hippocampal neuron growth.

The researchers noted that all male rats readily copulated when exposed to receptive females, with all of them engaging in sex. For the rats exposed to receptive females each day over the two week period, all had sex on numerous days but some did not do so every day.

Though research in rats is often used to better understand human behavior, the research findings cannot be used to directly explain sexual activity in humans, which is more complicated.

“There are so many other factors,” said Amelia Thomson-DeVeaux ’11, co-founder of the student group Let’s Talk Sex. “For some people, sex does reduce stress. For others, it creates stress.”

The researchers also noted in their study that previous experiments involving running have demonstrated similar neurological effects in both rats and humans.

Thomson-DeVeaux emphasized the many different ways that people experience sex. “Campus sexual culture complicates the implications of sexual activity in a way that makes this one particular finding not particularly relevant,” Thomson-DeVeaux explained. “We cannot look at [this study] in isolation.”

But Thomson-DeVeaux did not rule out the findings’ potential implications. “People have a lot of ways to cope with stress,” she said. “Sure, sex could be one of them.”