Objective: The aim of the present research was to evaluate the psychological well-being and quality of sleep in addicts under methadone treatment for at least 6 months.

Methods: A total of 40 individuals were selected through purposeful sampling method among the referring addicts to 2 addiction centers in eastern Tehran. Participants took the Ryff scale of psychological well-being (RSPWB) and Pittsburgh sleep quality index (PSQI).

Results: Results of multivariate and univariate variance analysis demonstrated that addicts with more than 6 months of abstinence have significant difference in psychological well-being and quality of life (P&le0.01) compare to addicts with less than 6 months abstinence period.
There was also a significant relationship between sleep and its dimensions (P&le0.01).

Conclusion: Addicts with abstinence period of more than 6 months have higher psychological well-being and better sleep quality than addicts with abstinence period of less than 6 months.