Impact of Antihistamines on Sleep, Cognition, and Daily Functioning: Evidence From Primary and Community Care

This study examined how antihistamine properties of blood-brain barrier penetration, central H₁ receptor binding, and sedative potential-relate to sleep quality, daytime sleepiness, cognitive failures, and functional impairment in adults managed in primary and community health settings, while accounting for sociodemographic, lifestyle, and stress-related factors.

A cross-sectional study was conducted in primary care and community health settings using a questionnaire that contained the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Cognitive Failures Questionnaire (CFQ), and Work and Social Adjustment Scale (WSAS). Antihistamine exposure was classified by blood-brain barrier penetration, central H₁ receptor binding, and sedative potential. Multivariable regression analyses were used to identify factors associated with sleep, cognition, and functional outcomes.

Of the 385 participants, 130 (33.8%) used first-generation antihistamines and 255 (66.2%) used second-generation agents. Of the used antihistamines, 130 (33.8%) were highly sedating, 26 (6.8%) moderately sedating, and 229 (59.5%) nonsedating. Multiple linear regression showed that fixed sleep schedules were associated with less poor sleep (PSQI, B = -0.62, P = .004), while recent stress was associated with worsened sleep quality (B = 0.96, P < .001). Daytime sleepiness (ESS) was significantly associated with higher stress (B = 1.38, P < .001), night-shift work (B = 1.26, P = .003), and sedative properties (B = -1.60, P < .001). Cognitive failures (CFQ) were associated with female sex (B = 4.67, P = .009), higher stress (B = 8.75, P < .001), night-shift work (B = 6.20, P < .001), and sedative properties (B = -5.84, P < .001). Functional impairment (WSAS) was significantly associated with stress (B = 4.43, P < .001), night-shift work (B = 2.62, P = .001), sedative properties (B = -3.21, P < .001), and symptom severity (B = 2.37, P < .001).

Antihistamine effects on sleep and cognition appear to be shaped by both sedative properties and patient characteristics. These findings suggest that prescribing practices should consider both symptom control and potential impacts on sleep health, cognitive performance, and social functioning, while recognizing that causality cannot be inferred without objective assessments and longitudinal designs.