A matter of the heart: Daytime relationship functioning and overnight heart rate in young dating couples

Background Although past longitudinal research demonstrates that romantic partners affect one another’s health outcomes, considerably less is known about how romantic experiences “get under the skin” in everyday life. Purpose The current study investigated whether young couples’ naturally occurring feelings of closeness to and annoyance with each other during waking hours were associated with their overnight cardiovascular activity. Methods Participants were 63 heterosexual young adult dating couples (Mage = 23.07). Using ecological momentary assessments, couples reported their hourly feelings of closeness to and annoyance with their partners across 1 day; subsequent overnight heart rate was captured through wearable electrocardiogram biosensors. Actor–partner interdependence models tested whether individuals’ overnight heart rate varied as a function of (a) their own daytime feelings of closeness and annoyance (actor effects) and (b) their partner’s daytime feelings of closeness and annoyance (partner effects) while controlling for daytime heart rate. Results Although young adults’ feelings of romantic closeness and annoyance were unrelated to their own overnight heart rate (i.e., no actor effects), gender-specific partner effects emerged. Young men’s nocturnal heart rate was uniquely predicted by their female partner’s daytime relationship feelings. When women felt closer to their partners during the day, men exhibited lower overnight heart rate. When women felt more annoyed with their partners during the day, men exhibited heightened overnight heart rate. Conclusions The findings illustrate gender-specific links between couple functioning and physiological arousal in the everyday lives of young dating couples, implicating physiological sensitivity to partner experiences as one potential pathway through which relationships affect health.