People who prefer to sleep late in the morning and stay up late at night have a higher-than-average risk of depression—a link that may be especially risky for people who have type 2 diabetes, since the two diseases are already so intertwined.
The new study, which was presented this week at the Endocrine Society’s annual meeting in Orlando and has not yet been published in a peer-reviewed journal, analyzed questionnaires about mood, sleep quality, and time preferences from 476 people in Chicago and Thailand who have diabetes. (The researchers wanted to include two different geographic locations, since sleep-wake preferences can vary based on distance to the equator.)
In both groups of participants, people who had a later chronotype—those who preferred to stay up late and do activities in the evening—reported more depression symptoms than those with early chronotypes. This was true even after the researchers adjusted for sleep quality, age, gender, and other factors that could affect depression rates.
The findings are important because depression is common in patients with diabetes, says lead investigator Sirimon Reutrakul, MD, associate professor at Mahidol University Faculty of Medicine in Thailand. What’s more, untreated depression can make it harder for people to manage their diabetes, she adds, and can contribute to poor self-care, poor blood glucose control, and diabetes complications.