New expert consensus highlights the role of circadian rhythms in treating bipolar disorder

A new consensus report published in the journal Bipolar Disorders details the specific knowledge about the body’s internal clock that mental health professionals need to provide the best care for patients with bipolar disorder. The findings provide a framework for using light, dark, and daily routines to help stabilize mood and improve sleep. This information is intended to help update clinical training and treatment guidelines around the world.

Bipolar disorder is a mental health condition characterized by extreme shifts in mood, energy, and activity levels. People with this condition experience emotional highs known as mania or hypomania, along with periods of severe depression. The exact causes of these mood episodes are complex and often vary from person to person. However, growing evidence suggests that disruptions in circadian rhythms play a significant role in the illness.

Circadian rhythms are the physical, mental, and behavioral changes that follow a 24-hour cycle. These daily rhythms are driven by an internal biological clock located in a brain region called the suprachiasmatic nucleus. This master clock responds to environmental cues like light and darkness. These environmental signals tell the human body when it is time to be awake and when it is time to sleep.

The study of how biological rhythms affect human health is known as chronobiology. Based on this science, researchers have developed chronotherapies. These are treatments that seek to adjust the body’s internal clock to improve mental and physical health. Typical chronotherapies include timing a person’s exposure to bright light or creating highly structured daily routines.

Basic science and observational studies suggest that circadian dysfunction is deeply intertwined with bipolar disorder. Treatment strategies based on this science are gaining recognition as helpful tools for managing the condition. Despite the growing evidence, many medical training programs overlook this topic. Experts note that the average medical student receives very little education regarding the science of sleep or biological rhythms.

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Many clinical practice guidelines also omit recommendations regarding chronotherapy. A previous review of 25 treatment guidelines for bipolar disorder found that less than half mentioned circadian disturbances at all. The authors of the current study wanted to bridge this educational gap.

“The science of chronobiology in mood disorders is almost 50 years old, during which we have learned a great deal! But despite this, most clinical guidelines for bipolar disorder and most clinical training programs make no or very little mention about the role of circadian rhythms in the management of the disorder,” said Jacob Crouse, a senior research fellow at the Brain and Mind Centre at the University of Sydney.

Crouse and his team set out to identify exactly what mental health clinicians should know about chronobiology to optimize patient care. “We wanted to change this by bringing experts together to agree on the ‘must-know’ information for clinicians, which could then help influence guidelines and training programs, as well as key research priorities where we still have major knowledge gaps,” Crouse explained.

To determine this essential knowledge, the scientists organized a Delphi study. This research method relies on a panel of experts who answer questionnaires across multiple rounds. After each round, the experts see an anonymous summary of what the group thinks, and they can adjust their own answers. The goal is to see if the group can reach a consensus on a specific and highly technical topic.

The researchers recruited 30 experts from 15 different countries across North America, South America, Europe, Asia, and Oceania. The group had an average age of 55.3 years and was 40 percent female. Most of the participants were practicing psychiatrists. The panel brought a wealth of knowledge to the project, with an average of 26 years of clinical experience and 22 years of research experience.

The scientists began by gathering statements about bipolar disorder and chronotherapy from existing scientific literature. They extracted an initial pool of 960 statements, which they refined down to 758 statements for the first round of rating. The experts then used a five-point scale to rate how important it was for a clinician to know each piece of information. The rating options ranged from essential to unimportant, with a neutral option for conditional situations.

The researchers defined a consensus as any statement that at least 80 percent of the experts rated as essential or important. Over the course of three rounds of voting, the experts reached a consensus on 342 different statements. These approved statements were divided into four major themes. The themes covered basic circadian science, circadian health, the chronobiology of bipolar disorder, and specific chronotherapies.

Within the basic science theme, the experts agreed that clinicians must understand how the human biological clock works. For example, all experts agreed that light is the strongest environmental cue for the human body. They also agreed that melatonin is a chemical signal of darkness, rather than just a simple sleep hormone. Light exposure inhibits the brain’s ability to synthesize this specific hormone, which naturally promotes wakefulness during the day.

Under the theme of circadian health and disruption, the experts identified the causes and consequences of a misaligned body clock. They agreed that shifting sleep and wake times is associated with greater mood instability. They also noted that increasing morning light exposure and reducing evening light exposure tends to help shift the biological clock to an earlier time. This simple behavioral adjustment can lessen the physical stress of irregular schedules.

The third theme focused on the specific links between circadian rhythms and bipolar disorder. The experts reached a consensus that a malfunctioning body clock may underlie the mood cycles seen in this condition. They agreed that seasonal changes, such as shifting daylight hours, are a common trigger for mood episodes. They also emphasized that poor sleep can worsen the symptoms of bipolar disorder, and that these symptoms can similarly interfere with a person’s ability to rest.

The final and largest theme covered six major chronotherapies. The experts agreed that mental health professionals need to know about the proper protocols, risks, and expected outcomes for each treatment. For instance, bright light therapy involves sitting near a specialized device that emits a specific intensity of light. The experts noted that this therapy provides evidence of acting as a strong antidepressant for the depressive phase of bipolar disorder.

Another approved treatment strategy is dark therapy, which often involves wearing special orange-tinted glasses. These blue-blocking glasses stop the specific wavelengths of artificial light that suppress natural melatonin production. The experts agreed that wearing these glasses in the evening can improve sleep and may help rapidly reduce symptoms of mania. They also agreed that patients should try to darken their bedrooms using blackout curtains or eye masks.

The experts also reviewed statements regarding the use of supplemental melatonin. They determined that there is currently insufficient clinical evidence to fully endorse or reject over-the-counter melatonin supplements for treating the acute phases of bipolar depression. However, they did agree that taking high-quality melatonin an hour before bedtime sends a strong signal to the circadian clock.

The experts also endorsed Interpersonal and Social Rhythm Therapy as an essential concept for clinicians to learn. This psychological treatment teaches people to track and manage the regularity of their daily routines. Patients monitor when they get out of bed, eat dinner, and go to sleep. The consensus statements noted that this therapy helps patients identify the specific environmental events that disrupt their daily rhythms.

Other chronotherapies discussed by the panel included wake therapy and sleep hygiene adjustments. Wake therapy involves controlled sleep deprivation under clinical supervision, which tends to work rapidly but requires extreme caution to avoid triggering mania. The panel also agreed on the utility of cognitive behavioral therapy for insomnia. This therapeutic approach addresses the specific thoughts and beliefs that interfere with healthy sleep.

The authors hope these details will eventually reach the wider public. “Most people will have a colleague, friend, or family member with bipolar disorder,” Crouse told PsyPost. “We want people to know that managing sleep and circadian rhythms is a critical part of managing bipolar disorder, and that not all clinicians know this.”

By spreading this knowledge, the researchers aim to empower patients to participate actively in their treatment. “We want people to be able to advocate for themselves to get the best care possible and to ask their doctor, ‘Do you know about this? What could we do about this?'” Crouse said.

A common misinterpretation among healthcare professionals involves the exact relationship between the biological clock and mental health. “Many people working in mental health assume that sleep and circadian rhythm disturbances are just secondary consequences of bipolar disorder,” Crouse explained. He suggests that this assumption has probably contributed to the topic being excluded from some guidelines and training programs.

“But sleep and circadian rhythm disturbances are strong triggers for mood episodes, and there is the hypothesis that these disturbances are actually a primary, causal part of the pathophysiology of bipolar disorder (at least in some people),” Crouse added.

One potential limitation of the study is the geographical makeup of the expert panel. The researchers did not recruit any participants from the African continent or from highly populated countries like India and China. They also lacked input from experts living in regions with extreme seasonal light changes, such as countries near the Arctic Circle. This lack of global representation suggests that some consensus statements might not account for unique cultural or environmental factors.

The makeup of the expert panel was also heavily skewed toward psychiatrists. Input from other healthcare professionals, such as general practitioners, psychologists, and mental health nurses, was limited. Bringing more diverse professional perspectives into the rating process might have shifted the priorities of the final consensus.

The researchers also noted the specific way they included patient perspectives. “Two young people with lived experience of bipolar disorder helped run the study, one of whom wrote about their journey with bipolar disorder and their perspective about how things might have been different for them had they encountered a clinician earlier who was aware of the chronobiological aspects of bipolar disorder,” Crouse said.

These individuals were also professional researchers, suggesting that incorporating a broader group of patients from the general community might yield additional insights into the practical limitations of these therapies. Still, Crouse emphasized the power of the included narrative. “This story is one of many, and helps communicate the urgency and reality of what we are trying to do,” he noted.

“A key mission is to get chronobiology much more onto the radar of people working in the field – not only for the mental health aspects but also for prevention and management of cardiometabolic health (which is a huge problem for people with bipolar disorder). We are keen that the field makes use of our consensus findings in their own training materials, and we hope to create accessible online modules that can enhance the skills of clinicians around the world,” Crouse added.

The study, “Essential Information About Chronobiology and Chronotherapy for the Optimal Care of People With Bipolar Disorders: An Expert Consensus,” was authored by Jacob J. Crouse, Victoria Loblay, Anthony Jorm, Timothy R. Wong, Zsofi de Haan, Carla Gorban, Mirim Shin, Emiliana Tonini, Chris Aiken, Lauren B. Alloy, Kürşat Altinbaş, Serge Beaulieu, Joanne S. Carpenter, Bruno Etain, Yuichi Esaki, Jess G. Fiedorowicz, Corrado Garbazza, Pierre A. Geoffroy, Bartholomeus C. M. Haarman, Tone E. G. Henriksen, Maria Paz Hidalgo, Maree L. Inder, Raymond W. Lam, Helle Ø. Madsen, Colleen A. McClung, Gunnar Morken, Laura Palagini, James Phelps, Richard J. Porter, Aswin Ratheesh, Rixt F. Riemersma-Van der Lek, Janusz K. Rybakowski, Erika F. H. Saunders, Peter F. J. Schulte, Daniel J. Smith, Holly A. Swartz, Bryan K. Tolliver, Anna Wirz-Justice, Ian B. Hickie, and John F. Gottlieb.