I have personally heard of circadian rhythm as it relates to the sleep cycle, but I had never heard of circadian depression. An interesting study published in The British Journal of Psychiatry explored how depression may involve different underlying factors. Although symptoms like fatigue, low mood, and low energy can look similar, depression may have several distinct subtypes. Researchers identified a potential new subtype that may involve the body’s internal clock. This disruption can affect sleep and create a perpetual state of jet lag.

The circadian clock is the body’s internal 24-hour rhythm. It manages hormones, digestion, mood, and sleep-wake cycles. As lead researcher Ian Hickie explained, disruptions to that clock can leave people feeling jet-lagged all the time. They may feel tired, exhausted, gain weight, have difficulty concentrating, sleep poorly, and experience changes in behavior.

In fact, researchers used data from the Australian Genetics of Depression Study. They found that nearly one in four participants with depression met the criteria for circadian depression. Participants had to meet at least three of the following six criteria to qualify for this potential subtype:

• Symptoms change with the seasons, including changes associated with shorter days and reduced natural light.
• The midpoint of sleep (the time halfway between falling asleep and waking up) occurs later than in the general adult population.
• Experience social jet lag, where sleep patterns don’t match the typical schedules that society follows.
• Have an evening chronotype. Research suggests that “night owls” may be more likely to struggle with anxiety and depression.
• Sleep longer than usual during depressive episodes.
• Report feeling very tired in the morning.

The key to this is that depression is not a uniform illness. Understanding the characteristics of different subtypes may help people access more effective treatments earlier. As study author Emiliana Tonini explained in a ScienceAlert article, recognizing these differences could help guide more personalized treatment.

Participants with this subtype reported poorer responses to certain commonly prescribed antidepressants. As a result, researchers suggest that treatments targeting the circadian rhythm may offer benefits. These could include light therapy, regular sleep-wake schedules, and melatonin-based treatments. However, researchers still need to investigate these approaches further to determine which treatments work best.

Now, what did they say about gaining weight?

Stay well and stay informed!