People who are neurotic often have more difficulty with relationships and marriage. But if neurotic newlyweds have frequent sexual relations, their marital satisfaction is every bit as high as their less neurotic counterparts, according to a study in the current Social Psychological and Personality Science.

Neuroticism is the tendency to experience negative emotion, and people who are high in it get upset and irritated easily, change their mood often, and worry frequently. People who score high in neuroticism are less satisfied in romance and relationships, and when they get married they are more likely to divorce. "High levels of neuroticism are more strongly associated with bad marital outcomes than any other personality factor," said Michelle Russell and James McNulty of the University of Tennessee, authors of the study.

But sex in marriage seems to make people happy -- other research has shown that sexual interactions improved the next day's mood. Russell and McNulty wanted to know if frequent sexual activity would erase the negative effects of neuroticism. They followed 72 newlywed couples over the first four years of their marriage; both spouses reported -- separately and privately -- on their marital satisfaction and sexual frequency every six months.

On average, couples reported sexual intercourse about once a week during the first six months of marriage, and about 3 times a month by the fourth year of marriage. Couples were considered satisfied when they agreed that they "have a good marriage" and "My relationship with my partner makes me happy."

Marital satisfaction was not associated with sexual frequency -- not at the start of the marriage, or four years later. Highly satisfied marriages sometimes had high levels of sexual activity, and sometimes low levels -- sexual contact alone was not a good indicator of marital satisfaction.

But Russell and McNulty found one important exception. For spouses with high levels of neuroticism, frequent sexual intercourse improved their marital satisfaction. The effect of frequent sexual activity was enough to completely wipe away the "happiness deficit" that neurotic spouses usually have. "Frequent sex is one way that some neurotic people are able to maintain satisfy relationships," the authors write. The newlywed period is a time when sexual relations are particularly important, and for some -- but not all -- frequent sex improves their happiness with the marriage. This happiness-by-sex effect occurred regardless of how strong or happy the marriage was at the beginning of the study -- frequent sex protects marital happiness for neurotic newlyweds.