Several studies, original and serious, have tried to establish relationships between marital status and state of health.
Cardiology delivers astonishing results. For example, living without a spouse after age 75 increases the risk of death by 25% in the year following a heart attack.
We know that blood pressure is intimately linked to the socio-professional environment. In a couple, the quality of the self-reported marital relationship (high, medium or low) is inversely proportional to blood pressure. Exercise electrocardiograms after mental stress reveal that the myocardium of single people is two to three times more sensitive to it than that of people living in a couple. In general, in women, widowhood degrades the cardiovascular profile.
In sedentary people, sexual activity leads to higher risks of sudden death and acute heart attack in single people than in matched people. However, regular sexual activity decreases this risk (as with physical activity). Life as a couple would then be an advantage, if we postulate that sexual activity is more regular there.
Marital status has many other implications for health. Life as a couple and, a fortiori, family life limit risky behavior and stimulate cognitive functions. Thus, the risk of dementia among single people is 50% higher than that of married people. This difference is not observed among the divorced. This is how !
The psyche is obviously concerned. Hospitalization for psychiatric reasons multiplies by five the risk of suicide of the spouse, in the following two years. The death of the spouse multiplies this risk by eight (always within two years); and if the death is due to suicide, this risk is multiplied by more than twenty.
Severe pain at the end of the day in one of the spouses reduces the quantity and quality of sleep of the other, with sleep that is all the less restorative the closer the marital relationship is. As for chronic pain, that of one objectively influences the state of health of the other.
If marriage is already widely known to increase the life expectancy of individuals, we know less about its repercussions in terms of public health. Prematurity and low birth weight of newborns are more common among single than married mothers. In a completely different register, marriage considerably reduces anti-social behavior; it reduces the risk of crime by about 35%, although Bonnie and Clyde still have too many emulators. Alas, feminicides come to tarnish this beautiful picture, because the spouse is the author four times out of ten.
I only mentioned studies that eliminated confounders. It is therefore not a matter of correlations, but of health causalities, which in no way presume the advantages and disadvantages of celibacy in other areas.