Research Links Hypothyroidism to Increased Severity of Sleep Apnea

The UNIFESP team analyzed data from 761 São Paulo residents who underwent polysomnography, the standard test for evaluating sleep conditions. Of the participants, 12.6% were diagnosed with hypothyroidism, and nearly half of these individuals (49.5%) were also found to have OSA. The findings have been published in the journal SLEEPJ.

First author Ellen Maria Sampaio Xerfan noted that the prevalence of sleep apnea in their study exceeded previous literature estimates, which typically cite a 30% to 40% prevalence in people with hypothyroidism.

Hypothyroidism, characterized by inadequate hormone production from the thyroid gland, often results from Hashimoto's thyroiditis, an autoimmune disorder. Symptoms may include fatigue, weight gain, and difficulty concentrating. The estimated prevalence of hypothyroidism ranges from 4% to 8% in various populations.

Obstructive sleep apnea leads to interrupted breathing during sleep, causing drops in oxygen levels and fragmented rest. These interruptions result in symptoms such as daytime sleepiness and are associated with greater risks for cardiovascular and metabolic diseases.

The researchers are exploring the intricate relationship between thyroid function and sleep, emphasizing their roles in maintaining bodily homeostasis. According to Xerfan, both systems interact significantly, with disturbances in one potentially affecting the other. Their analysis showed that participants with hypothyroidism had more disrupted sleep patterns, while elevated TSH levels correlated with more severe forms of OSA.

Monica Levy Andersen, the study adviser, underscored the necessity for a more integrated approach to sleep issues in clinical care. She noted that while sleep disorders are often overlooked, they significantly impact a patient's overall health, including metabolic and hormonal changes.

The study also assessed the effects of hormone replacement therapy on sleep in hypothyroid patients, revealing that those receiving treatment averaged 49 minutes more of sleep and 22 additional minutes in deep sleep compared to untreated individuals. This improvement suggests positive impacts on sleep quality from medication.

Researchers caution that although treating hypothyroidism may enhance sleep parameters, it does not replace the need for specific evaluation and treatment of sleep apnea. Given the compounded cardiovascular risks associated with both conditions when untreated, proper diagnosis and management for both are crucial.

Xerfan concluded by urging healthcare professionals to consider the interplay of thyroid function and sleep disorders in patient assessments to improve overall health outcomes.