Circadian depression linked to sleep habits, new research finds

A person’s sleep habits may help identify a new subtype of depression linked to the body’s internal clock.

In a study of 11,380 Australian adults with a history of depression, about 23% met the researchers’ criteria for what they call “circadian depression.”

The profile included at least three of six characteristics: being an evening person, waking up very tired, sleeping longer during the worst periods of depression, experiencing seasonal changes, having a later midpoint between falling asleep and waking up, and experiencing “social jet lag,” a significant shift in sleep pattern between work days and days off.

Seasonal changes may include sleep, mood, activity, appetite, weight, or energy.

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The study, published Oct. 20 in the British Journal of Psychiatry, could potentially help guide more personalized care for patients with depression, researchers say.

“Depression is not a uniform illness, and understanding the characteristics of different subtypes means we can give people quicker access to treatments that will be most effective for them,” first author Emiliana Tonini, Ph.D., of the Brain and Mind Center at the University of Sydney, said in a statement.

Researchers are studying whether disrupted sleep-wake rhythms could help identify a proposed subtype of depression. (iStock)

However, the label does not constitute a formal diagnosis and requires independent replication and further study, the researchers noted.

Questions about treatment

People in the circadian group reported an earlier onset of depression and more severe symptoms than those who did not meet the criteria. They were also more likely to report weight gain during depressive episodes.

They also reported poorer responses and more side effects with two common classes of antidepressants, selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs).

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Participants reported how well their medications worked, but the study did not explain why some were less effective and did not test treatments aimed at adjusting the body’s internal clock.

Researchers said light exposure, regular sleep schedules and melatonin-related approaches warrant further study.

The proposed circadian profile includes characteristics such as waking up very tired, oversleeping during depression, and being an evening person. (iStock)

Dr Ian Hickie, co-author of the study and professor of psychiatry at the University of Sydney, said the proposed profile “cuts across existing historical subtypes” of depression, most commonly atypical and bipolar depression, as they share characteristics such as low energy and excessive sleep.

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Atypical depression may also involve weight gain, while bipolar depression refers to depressive episodes in people with bipolar disorder, which also involve periods of unusually high or irritable mood and increased energy.

“We define circadian rhythm just by sleep-wake and circadian characteristics,” Hickie told Fox News Digital.

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For some people with this profile, Hickie said sleep-wake disturbances can be more than a symptom of depression. “This type of circadian disruption is not simply a consequence, but the underlying cause,” he writes.

The study itself, however, could not establish whether a disruption in the body clock caused or resulted from depression.

Going to bed late or having trouble waking up does not in itself mean a person has depression, the researchers noted. (iStock)

Going to bed late or having trouble waking up does not necessarily indicate depression. Participants had previously reported depression, which in some cases was severe, recurrent, or long-lasting.

Participants in the circadian group also reported more manic experiences. John Puls, a psychotherapist and assistant professor at Florida Atlantic University, said these symptoms could help explain their response to antidepressants.

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“SSRIs are not intended to treat these larger mental health symptoms that go well beyond depressive symptoms,” Puls, who was not involved in the study, told Fox News Digital. “In fact, some SSRIs can make manic symptoms worse, leading to poor sleep.”

Limitations of the study

The study had several limitations, the researchers acknowledged.

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Participants reported their own sleep habits and treatment experiences, and cross-sectional analysis did not show whether sleep disturbances preceded or followed depressive symptoms.

All participants were of European ancestry, so the results may not apply to other populations.

The researchers used six sleep-related characteristics to identify the proposed circadian depression profile, including social jet lag and being an evening person. (iStock)

Jillian Amodio, a Maryland-based psychotherapist and founder of Moms For Mental Health, cautioned against using the findings as “a benchmark for treating every person the same.”

“Biological, environmental, social and psychological factors all need to be considered,” Amodio, who was not involved in the research, told Fox News Digital.

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Researchers should look at more populations, including people who work night shifts, and take into account differences in time zones and seasons, according to Amodio.

The study was led by researchers from the University of Sydney and the QIMR Berghofer Medical Research Institute, with co-authors from institutions in Australia, the United Kingdom and the United States.