Opposite of the commonly held belief that laughter lowers blood pressure, Martin (2002, p. 218) ...

More positive results are found for using coping humor, a strategy of using humor to cope with stress. For example, Kuiper and his colleagues (Kuiper, Grimshaw, Leite, & Kirsh, 2004) demonstrated that coping humor is linked to higher levels of self-esteem, perceived competency, and positive affect as well as less anxiety, depression, and negative affect. Further, they demonstrated that some sense-of-humor styles are associated with positive psychological well-being such as affiliative humor (e.g., I laugh and joke a lot with my friends) and self-enhancing humor (e.g. Even when I'm by myself, I am amused by the absurdities in life), whereas others are associated with negative psychological well-being such as self-defeating humor (e.g., I often get carried away in putting myself down if it makes my family and friends laugh) and belabored humor (e.g., I react in an exaggerated way to mildly humorous comments) (Kuiper et al., 2004, p. 147). Their ironic conclusion is listed in the title of their article that reads Humor is not always the best medicine (p. 135).