Depression is an illness that affects mood. A new Australian study suggests that one form of depression may have a link to the body's daily clock. This clock helps control when people sleep and wake up. Researchers studied information from 11,380 adults. About one in four, or 2,604 people, fit the proposed form of depression.
People in this group had at least three of six signs. These included sleeping late, sleeping too much, feeling tired after waking, and changes in mood with the seasons. The other signs were a preference for evenings and different sleep times on workdays and free days. Their depression started at about age 19, compared with about 23 for the other people. They also said common medicines for depression helped less and caused more unwanted effects.
The researchers think treatment with bright light or melatonin, a substance that helps control sleep, might help. But this form of depression is still a proposal. People described their own sleep habits. Those answers do not prove that their body clocks work differently. Researchers need more studies to test treatments before doctors can use these findings to guide care.
