The unequal division of cognitive labor within the household and its potential association with mental load gained substantial interest in recent academic and popular discussions. Here, we aim to deepen this debate theoretically and empirically. First, we connect the debate about cognitive household labor with existing stress theories, which enables us to reflect, which types of cognitive labor are especially stressful. We then discuss, whether women perform these types more often, making them more prone to experience higher levels of exhaustion because of household labor. Thus, we go beyond the question, whether the division cognitive labor is gendered and ask in addition whether men and women typically perform cognitive labor that are differently stressful. Second, we offer a quantitative measure of cognitive labor and analyze the gendered association between the division of cognitive labor in the household and exhaustion using large-scale survey data from seven European countries within the Generations & Gender Program (GGP). Our results confirm that a high share of cognitive labor with households is especially detrimental for women but not for men. Unequal division of physical labor, by contrast, does not have similar negative effects on women’s exhaustion. We use these analyses to discuss future directions in the conceptualization and measurement of cognitive labor in the household and its implications for mental load. In doing so, this paper lays the foundations for a comprehensive data-driven understanding of the implications of unequal division of cognitive labor in the household for gender inequality.