ABSTRACT Insomnia disorder is the most common sleep disorder in the general population, with higher prevalence in women. Three specific periods in a woman's life—puberty, pregnancy and menopause—seem to be associated with marked gender differences in insomnia prevalence. Puberty is a critical stage for the development of insomnia, with an increase in its prevalence among girls after menarche. During pregnancy and the postpartum period, women also report a rise in insomnia symptoms. Various factors, including hormonal, physiological, relational, emotional and environmental ones, can affect sleep during these sensitive times. Furthermore, the transition to menopause tends to exacerbate gender differences in insomnia prevalence, as it is associated with the emergence of physiological and psychological symptoms (e.g., hot flashes, sleep disturbances and mood changes) that can impair sleep. Thus, biological and psychosocial factors seem to explain gender differences in insomnia prevalence and characteristics throughout the lifespan. Considering this framework, this review aims at summarising and deepening the existing empirical literature on gender differences in sleep physiology, insomnia prevalence and clinical characteristics, and predisposing, precipitating and perpetuating factors for insomnia disorder, in different ages throughout the lifespan. Attention is also given to sexual minority groups, providing a snapshot of sleep difficulties and insomnia symptoms among transgender people. Although the topic is relevant, available literature is still quite scarce. The investigation of gender differences in insomnia disorder could be useful to better understand its prognosis and outline an appropriate and personalised treatment.