Thomeer's research focuses on how relationships influence and are influenced by physical and mental health, with particular attention to gender and sexuality. Overarching themes include caregiving, chronic conditions, and marriage. For example, Thomeer's past studies consider how one person's depression impacts his/her spouse's mental health, what intimacy looks like in gay, lesbian, and straight relationships, how nursing home admission rates differ across racial/ethnic groups, and how parenthood changes health habits.
Shows that sexual minority status, as indicated by sex of sexual partners, is associated with self-rated health, although socioeconomic status suppresses this association as respondents with same-sex partners reported worse health than those with only different-sex partners only when taking into account socioeconomic status. Finds that age and sex moderated this relationship: having any same sex partners was associated with worse health for women but not men and among younger adults only.
Examines how gay, lesbian, and heterosexual couples discuss their end-of-life plans with each other, and finds that same-sex spouses devote intensive time and attention to informal planning conversations and formal end-of-life plans whereas heterosexual spouses report minimal formal or informal planning. Finds that the primary reasons same-sex spouses give for making end-of-life preparations are related to the absence of legal protections and concerns about family interference.
Discusses how multiple chronic conditions (i.e. multimorbidity) in one spouse increases the other spouse's depressive symptoms, with this association stronger when men have chronic conditions than when women have chronic conditions. Shows that this association is more pronounced for some chronic conditions (lung disease, stroke, diabetes) than others, although again this depends on the gender of the ill spouse.
Finds that wives provide emotion work regardless of their own health status (e.g. even when ill themselves). Finds that husbands provide emotion work less consistently, typically only when the husbands see themselves as their wife's primary source of stability or when the husbands view their marriage as balanced, because notions of traditional masculinity preclude some husbands from providing emotion work even when their wife is health-impaired.
Investigates how health- and disability-based need factors and enabling factors (e.g. socioeconomic and family-based resources) relate to nursing home admission among three different racial and ethnic groups. Highlights that racial-ethnic differences in nursing home admission are magnified after controlling for health- and disability-based need factors and enabling factors, and the degree to which specific factors contribute to risk of nursing home admission varies significantly across racial-ethnic groups.
Finds substantial disparities between Black and White adults, especially pronounced among men, in the quality of close relationships and in the consequences of these relationships for health. Discusses how greater childhood adversity helps to explain why Black men have worse health than White men in mid- and late-life, and some of this effect appears to operate through childhood adversity's enduring influence on relationship strain in adulthood.