In the report published by Jama Psychiatry, it's unclear whether those who are already early risers could benefit from getting up even earlier.
According to the study, waking up at least one hour before the usual time could reduce the risk of depression by 23 percent. The researchers at the University of Colorado Boulder and the Broad Institute of MIT and Harvard conducted the study on almost 840,000 adults of European ancestry, the Hindustan Times reported.
A report by The National Center for Biotechnology Information dated September 2008 on 'sleep disorders as core symptoms of depression' highlights a study performed by The National Institute of Mental Health Epidemiologic Catchment Area 20 years ago. During the investigation, 7954 adults were interviewed in a group of two a year apart, and this study first highlighted the strong association between sleep disturbance and subsequent depression. They found that 14 percent of the people who had insomnia at the first interview developed new major depression the following year.
The NCBI study concludes that there is a need for more successful management of sleep disturbance in patients suffering from depression to improve quality of life and reduce depressive relapse and recurrence. The report majorly talks about the relationship between sleep and depression and not specifically about waking up early and its correlation with depression.
According to a report published in 2018 by Vetter, a long-term study of 32,000 nurses showed that "early risers" were up to 27 percent less likely to develop depression over four years. According to the author of the report Dr. Iyas Daghlas, "Our genetics are set at birth, so some of the biases that affect other kinds of epidemiological research tend not to affect genetic studies." Dr. Daghlas, a Harvard Medical School graduate, further said that more than 340 common genetic variants, including variants in the so-called "clock gene" PER2, influence a person's chronotype. "The genetics collectively explains 12-42 percent of our sleep timing preference", the HT report quoted Daghlas as saying.
However, considering the published report by Jama Psychiatry, it's unclear whether those who are already early risers could benefit from getting up even earlier. But, shifting to an earlier bedtime would likely be helpful for those in the intermediate range or evening range. Thus, the claim that waking up early in the morning could reduce the risk of depression is partly true.