An examination of the efficacy of chronotherapeutics as a treatment for mood disorders

• Main Author: Ramroop, Lisa
• Other Authors: Soghomonian, Jean-Jacques
• Language: en_US
• Published: 2019
• Subjects: Medicine
• Online Access: https://hdl.handle.net/2144/34882

The body is influenced by the earth’s day and night cycling. Various biological systems within the body have different activity and rest cycles during a 24-hour period. This is often referred to as the body’s circadian rhythm. The autonomic nervous system, cardiovascular system, hepatic and renal system, to name a few, all depend on the carefully calibrated timings of the body’s internal clock. Variations or abnormalities in this normal rhythm can lead to the development of an assortment of disease states and pathologies. One disease state that readily exemplifies the connection between disordered circadian rhythms and pathology is that of mood disorders like depression. There is a bi-directionality in cause and effect; desynchronized circadian timing can contribute to the development of mood disorders, while certain symptoms present in mood disorders can create or exacerbate irregular circadian rhythms. Mood disorders are serious disease states and are the number one cause of disability worldwide. The conditions can often be chronic, recurrent and debilitating for their sufferers, leading to further health issues, loss of productivity and function in society and increasing the likelihood of death, either through corresponding health conditions or in some instances, suicide. The number of people being diagnosed with mood disorders is increasing every year, and those who are aware of their status oftentimes are still suffering with symptoms. Various treatment options have been utilized, most commonly pharmacological therapy in the form of prescription medications, or psychotherapy. However, these treatment options face limitations in efficacy, safety, and speed of action. Chronotherapeutics, or the use of external environmental stimuli to retrain the body’s biological clock, is being examined as a potential treatment for mood disorders. These chronotherapeutic treatments include sleep deprivation, bright light therapy, blue light blocking glasses and melatonin supplementation. Sleep deprivation has been shown to be helpful in treating the symptoms of major depressive disorder and bright light therapy alleviates symptoms of seasonal affective disorder, major depressive disorder and bipolar depression--even in vulnerable populations. Melatonin has shown usefulness in resetting circadian rhythms, while blue light blocking glasses accomplish the same, along with decreasing the severity of manic episodes in bipolar depression. A combination of chronotherapeutic approaches has proven the most effective of all, able to treat seasonal affective disorder, major depressive disorder and bipolar depression, with a longer lasting respite from symptoms and offering an alternative to those who have been previously non-respondent or resistant to other conventional treatment options. Lack of clinician knowledge about chronotherapeutic options, as well as limitations in the availability of chronotherapeutic devices in hospital settings currently limit accessibility to treatment. More research also needs to be done to further illuminate the mechanistic actions that underlie the body’s circadian timings. Chronotherapeutics proves itself as a useful tool in the battle against mood disorders and should be more readily utilized as a treatment option in the future.