New research, in plain words.

October 21, 2026 · Depression · Sleep

A “body clock” pattern of depression?

Promising

What they found

Researchers in Australia looked at about 11,400 adults with severe or repeated depression. About 1 in 4 had a cluster of body-clock signs: sleeping much more when depressed, feeling very tired after waking, being a strong night owl, sleeping very late on days off, and mood that shifts with the seasons. In this group, depression started younger (about 19 instead of 23), symptoms were more severe, and people said common antidepressants (SSRIs and SNRIs) helped a little less.

How strong is it?

One large study, based on what people reported about themselves at one point in time. Not yet repeated by other teams, and not an official diagnosis.

What it means for you

If your depression comes with long sleep, late nights or seasonal swings, mention it to your doctor. Body-clock treatments such as light therapy and steady wake times are already used for some depression. Do not change any medicine because of this study.

What other experts say

Independent experts note that these signs overlap with depression with “atypical features,” that long sleep may not be a body-clock sign at all, and that most people studied were women of European descent.

In the news: ABC News (Australia) · The Guardian