Case Report: Resolution of Insomnia in a 32-Year-Old Male with Generalized Anxiety Disorder Following Discontinuation of Mint-Flavored Toothpaste

Background: Insomnia is a common sleep disorder frequently comorbid with anxiety and is often attributed to psychophysiological hyperarousal. While internal and behavioral factors are typically emphasized, environmental sensory exposures are less commonly recognized as potential contributors to sleep disturbance. Menthol, a widely used compound in oral hygiene products, activates transient receptor potential melastatin 8 (TRPM8) receptors, which are known to influence acute sensory and arousal responses. However, their role in chronic sleep disturbance remains unclear. Aim: This case report aims to describe a possible association between nightly menthol exposure from mint-flavored toothpaste and insomnia, and to highlight the potential role of sensory environmental factors in sleep disturbance among susceptible individuals. Case Presentation: A 32-year-old male with a history of generalized anxiety disorder presented with a 7-month history of difficulty initiating and maintaining sleep. The onset of insomnia occurred shortly after the patient began using a mint-flavored toothpaste exclusively at night. No other precipitating factors, including medication changes, psychosocial stressors, or poor sleep hygiene, were identified. Following discontinuation of the mint-flavored toothpaste and substitution with a non-mint formulation, the patient experienced rapid and sustained improvement in sleep latency, nighttime awakenings, and overall sleep quality. Conclusion: This case describes a possible association between menthol exposure from mint-flavored toothpaste and insomnia in a patient with anxiety. While causality cannot be established from a single case, the temporal relationship and symptom resolution following discontinuation suggest that menthol-containing products may contribute to sleep disturbances in susceptible individuals. These findings highlight the importance of considering environmental and sensory factors, including menthol exposure, in the evaluation of unexplained insomnia, particularly among individuals with heightened sensory sensitivity. Further research is warranted to explore this potential relationship. Keywords: insomnia, menthol, toothpaste, sleep initiation and maintenance disorders, anxiety disorders, transient receptor potential channels