The adverse effects of SSRIs stem from excessive stimulation of 5-HT receptors: overactivation of 5-HT2A/2C receptors induces sexual dysfunction, with reported incidence rates of 24–73% in SSRI-treated patients (25, 26); agonism at 5-HT3 receptors mediates nausea and vomiting (27); activation of 5-HT1A receptors enhances alertness while reducing REM sleep, resulting in sleep disturbances (28). Here, HTR1A is linked to sleep disorder.