A new study has concluded that taking the drug modafinil, typically used to treat sleep disorders, in combination with antidepressants reduces the severity of depression more effectively than taking antidepressants alone. The study, a collaboration between the Universities of Cambridge and East London and King’s College London, was published online in the Journal of Clinical Psychiatry.

“Modafinil has actions on a number of neurotransmitter systems. This may explain why adding it to traditional antidepressants, such as selective serotonin reuptake inhibitors, has beneficial effects on the symptoms experienced by depressed patients,” says Professor Barbara Sahakian from the University of Cambridge in a release.

For the research, the scientists reviewed various studies that had examined the use of modafinil as an add-on treatment for depression. The meta-analysis involved a total of 568 patients with unipolar depression and a total of 342 patients with bipolar depression. The analysis revealed that modafinil improved the severity of depression as well as remission rates. Modafinil also showed beneficial effects on fatigue and sleepiness, with the added benefit of the comparable side effects to placebo.