NEARLY ONE IN four cases of depression may fall into this category. A study published in the British Journal of Psychiatry identified “circadian depression,” and people with it have an internal 24-hour clock that’s out of sync with their external environment.
Like really out of sync. We’re not talking about jet lag. This is when your body’s internal timing network just can’t regulate your body’s systems.
It's important to get this out of the way upfront: Circadian depression isn't in the DSM-5—the “psychiatry bible” mental health professionals use to make diagnoses. In other words, it's not an official condition yet. But it’s important to know about. We had mental health experts break it down.
What Is Circadian Depression?
CIRCADIAN DEPRESSION IS a subtype of depression caused by circadian disruption, which is when your body’s circadian rhythm doesn't align with your external environment. People with circadian depression have disrupted sleep-wake cycles, lower levels of daytime activity, low energy, and weight gain during depression episodes, according to the study.
People who were classified in the study as having circadian depression were more likely to have severe symptoms of depression, including:
- Bipolar-like features such as mania
- Suicidal thoughts
- Psychological distress
- Physical symptoms like pain or fatigue
- Weight gain during episodes
People with circadian depression also seem to be more likely than those with other forms of depression to have other conditions like ADHD, anxiety, bipolar disorder, obesity, or insulin resistance.
What Did the Study Find?
THE STUDY’S RESEARCHERS analyzed clinical and genetic data from more than 10,000 Australians with depression. To determine whether people had the proposed subtype, circadian depression, rather than general depression, they looked at factors like a person's social jetlag (the mismatch between their internal clock and external schedule), whether they were night owls, how tired they felt in the morning, and whether they experienced excessive daytime sleepiness. They also looked at whether people had poor responses to antidepressant treatment, and people with severe symptoms that were a mix of bipolar disorder, depression, and somatic disorders.
About 23 percent of participants fell into the category of circadian depression. This is more than a label. It’s important to recognize because, as the researchers pointed out, people with circadian depression tend to be less responsive to traditional antidepressant medications. That means treatment tailored to their subtype is especially important.
What Causes Circadian Depression?
A FEW THINGS are happening here. First is people’s sleep schedules getting thrown off, possibly from chronic inflammation and a messed-up metabolism. There is prior evidence of a link between circadian rhythm and these two factors (though researchers are still on the fence on what causes what).
“The body’s internal clock helps coordinate changes in the brain throughout the day," says Hillary Ammon, PsyD, clinical psychologist at the Center for Anxiety and Women’s Emotional Wellness. That includes a feeling of alertness and motivation during conventional waking hours. When the timing is off, these coordinated changes are also affected.
“Increased tiredness, low motivation, or decreased focus can all be factors that lead to depression and also be traits of depression,” says Ammon. Having an internal clock that's off schedule also impacts your metabolism and stress hormone cortisol.
Increased cortisol release at night can lead to an increase in unease and difficulty sleeping. Changes in metabolism rates can cause weight gain. Weight gain and decreased activity are classic symptoms of depression.
The concept of circadian depression is not an entirely new idea, says Aaron P. Brinen, PsyD, assistant professor of psychiatry and behavioral sciences at Vanderbilt University Medical Center. “We've known that there is a link to sleep in a number of different psychiatric disorders, including depression,” he says. “When people are depressed, their sleep gets disrupted and vice-versa—when sleep is disrupted, you're more likely to get depressed.”
How Is Circadian Depression Treated?
SINCE CIRCADIAN DEPRESSION was just discovered, there is no set treatment for it yet. But doctors who treat depression say the new discovery is a huge reminder that depression requires tailored treatments.
In the study, for example, the researchers found that people with circadian depression didn’t respond as well to standard antidepressants like SSRIs or SNRIs. In fact, people who meet the criteria for circadian depression might experience more side effects on these medications. Their suggestions? Treatments like light therapy and melatonin may reset the body's internal clock and ease symptoms.
Therapists spend a bit of time with the client anyway trying to pinpoint the drivers of their depression, says Brinen. “If it's being driven by sleep or sleep disruption, you're going to target that.”
The basics around mental health still stand. If you're having symptoms of depression, talk with a mental health professional about an evaluation and appropriate treatment. Plus, don’t be an armchair therapist and try to diagnose yourself. “I would be more mindful of the symptoms versus the diagnosis,” says Ammon.
Your provider can give you a full evaluation and recommend appropriate next steps tailored to your situation. “It may be that you need to be more thoughtful about sleep, travel, and work schedules,” Brinen says. It’s “just like when a person who is naturally hypoglycemic needs to carry snacks. You want to make sure you're prioritizing sleep.”
Korin Miller is a seasoned freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Everyday Health, Food & Wine, and more. She has a master’s degree from American University and lives by the beach.