OBJECTIVES Our study aims to identify socioeconomic factors related to insomnia prescription patterns in US outpatient settings. METHODS This project proposes a secondary data analysis using a national longitudinal database from 2004 National Ambulatory Medical Care Survey (NAMCS). Study subjects were derived from outpatient visits in which at least one insomnia drug was prescribed. A series of weighted chi-square statistics were performed to compare insomnia drug uses across various physician and patient characteristics. All analyses used SAS statistical software and incorporated sample weights and standard errors correction. RESULTS Among the 910 million outpatient visits that took place in the US in 2004, an estimated 24.98 million visits included at least one insomnia drug prescription. The majority of prescriptions were allocated to antidepressants (52.3%), which were more frequently prescribed than non-benzodiazepines (34.1%) and benzodiazepines (13.6%). Differences in drug pricing may explain these findings: the average wholesale price (AWP) for antidepressants is lower ($0.31) than non-benzodiazepine hypnotics ($2.52). Patient comparisons by insurance type revealed that Medicaid patients were less likely to receive the relatively expensive non-benzodiazepines (27.55%) than Medicare (32.53%), self-pay (33.39%), and private insurance (35.03%) patients. Prescribing patterns were significantly influenced by physician specialty (P=0.0001), with general/family physicians contributing the greatest frequency of insomnia prescriptions (36.1%). Females received significantly more insomnia prescriptions than males (16.4 mil. vs. 8.58 mil.; P <0.0001) and Black/Hispanics received significantly fewer insomnia prescriptions than did white patients (10.78% vs. 87.13%, P <0.0001). CONCLUSIONS Our findings indicate significant socioeconomic disparities in the use of insomnia prescriptions. While drug pricing might account for some of our results, marketing—particularly the sociodemographic and physician characteristics toward which such efforts are targeted—provides another strong explanation for prescription pattern disparities. Further evaluation of current practice guidelines and development of more manageable regulations might ensure greater consistency in treatment patterns.