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Endocrine Care: E. O. Bixler, A. N. Vgontzas, H.-M. Lin, S. L. Calhoun, A. Vela-Bueno, and A. Kales Excessive Daytime Sleepiness in a General Population Sample: The Role of Sleep Apnea, Age, Obesity, Diabetes, and Depression J Clin Endocrinol Metab 2005; 90: 4510-4515 [Abstract] [Full text] [PDF]

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Depression and EDS: rather a side effect of therapy than a causative relationship

Barna Vasarhelyi, Istvan Kocsis and Andras Treszl   (29 September 2005)

Depression and EDS: rather a side effect of therapy than a causative relationship 29 September 2005
Barna Vasarhelyi, associate professor Research Laboratory of Pediatrics and Nephrology, Hungarian Academy of Sciences, Istvan Kocsis and Andras Treszl Send letter to journal: Re: Depression and EDS: rather a side effect of therapy than a causative relationship vasbar{at}gyer1.sote.hu Barna Vasarhelyi, et al.	We read with great interest the paper by Bixler et al (1), showing that the presence of excessive daytime sleepiness (EDS) is more strongly associated with depression and metabolic factors than with sleep disordered breathing or sleep disruption per se. The authors concluded that EDS can be a presentation sign of depression and diabetes. Thus, patients with a complaint of EDS should be thoroughly assessed for depression and obesity/diabetes. However, we feel that this conclusion cannot be entirely supported by the methods employed in the study. Because the diagnosis of depression was based on self-report, only those subjects reported the disease who were aware of it, treated for it or had a history of suicide thoughts/attempts. In addition, the diagnosis of diabetes was based on self-report or on only one fasting blood sugar level test, which does not fulfill state of the art criteria for the diagnosis of diabetes. The percentage of diabetic patients discovered in the study by measuring fasting blood sugar level were not provided, and according to the paper, only those were included in the diabetic group who reported treatment for diabetes (see Results section). Since sleepiness and sleep disruption are well known side effects of anti-depressant therapy, it is possible that the higher incidence of EDS is rather a side-effect of therapy than result of depression. It would be interesting to study whether the type of treatment, administered drugs and the presence of EDS are related. Finally, depression is often not recognized for a long time, and a great proportion of patients are not treated for years. It is not clear from the paper whether these subjects were enrolled into the “not Depressed” group, having a lower incidence of sleep disruption. Speculatively, if the disease had been diagnosed earlier, the incidence of EDS could have changed in the control group. What did the authors do to identify these patients? In conclusion, we believe that although the link between EDS and depression or diabetes is an important issue. However, the limits of this study render it unable to establish these relationship with certainty. The paper’s conclusion that patients with a complaint of EDS should be thoroughly assessed for diabetes is questionable since only treated diabetic patients were studied. 1. Bixler EO, Vgontzas AN, Lin H-M, Calhoun SL, Vela-Bueno A, Kales A. 2005 Excessive Daytime Sleepiness in a General Population Sample: The Role of Sleep Apnea, Age, Obesity, Diabetes, and Depression. J Clin Endocrinol Metab 90:4510-4515