The authors present results of study concerning risk factors of sleep initiation and maintenance disorders in mental workers residing in Moscow — governmental institutions staffers and medical workers. To evaluate insomnia severity, the authors used questionnaire «Index of insomnia severity», studied work conditions and work-related stress intensity. The study results prove leading role of work intensity and stress at work in sleep disorders formation. The governmental employees demonstrated positive correlation between integral parameter of work intensity and insomnia severity index (r=0.43). Findings are that work-related stress which was evaluated via psycho-social characteristic of work increases insomnia risk (OR=2.3). Among environmental factors, the maximal role in insomnia formation is played by acoustic factor (OR=1.41). Moreover, somatic disorders were statistically connected with insomnia (OR=1.3). Shares of separate risk factors of chronic insomnia appeared to be age-related. The data obtained enable to optimize complex of measures to prevent chronic insomnia in workers.