Mechanisms and Clinical Applications of Cooling Interventions for Sleep

Thermoregulation is essential for sleep, with the nocturnal core body temperature decline triggering sleep onset and modulating sleep architecture. Disruptions to this thermal balance cause fragmented sleep and reduced sleep quality. Preliminary evidence suggests cooling may reduce hyperarousal, shorten sleep onset latency, and improve sleep continuity through multiple mechanisms, including enhanced distal-proximal skin temperature gradient, parasympathetic activation, and hypothalamic-pituitary-adrenal axis modulation. However, most studies are small (n<30), short-term (1-4 weeks), and lack standardized protocols or long-term follow-up. This narrative review evaluates evidence on cooling mechanisms (thermoregulatory and stress-related) and evaluates environmental and targeted cooling approaches (mattress systems, forehead devices) for insomnia, anxiety, post-traumatic stress disorder, and migraine. Across conditions, cooling shows promise for reducing hyperarousal and improving sleep outcomes, though evidence quality varies substantially. Critical research gaps include the absence of trials combining cooling with behavioral treatments such as Cognitive Behavioral Therapy for Insomnia, no trials in some clinical populations, limited biomarker-guided personalization, and uncertain long-term effects. Rigorous trials with active controls, objective endpoints, phenotypic stratification, and long-term follow-up are needed to establish cooling as an evidence-based intervention.