Depression and loneliness may predict work inefficiency among professionally active adults.

"Declarations Conflict of interestThe authors have no conflicts of interest to report. Conflict of interest The authors have no conflicts of interest to report."

"This publication is based on the results of the fourth stage of the multi-annual program “Improving safety and working conditions”, financed in 2017–2019 in the field of research and development from the funds of the Ministry of Science and Higher Education/National Centre for Research and Development. Program coordinator: Central Institute for Labor Protection – National Research Institute (PBiWP-IV/2017 Sub-contract No. TP-48/2017/PW-PB project I.N.08). PB, ŁŚ and HSJ devised the concept and procedure of the study. PB and HSJ collected the data. ŁM and PŚ performed the statistical analysis and interpreted the data. ŁM, PŚ and HSJ prepared the manuscript. All authors have approved the final article. The database used to support the findings of this study may be released upon application to the corresponding author. The authors would like to express their gratitude to Marta Robson for providing language assistance."