People with sleep apnea often snore loudly, wake up feeling unrefreshed, and experience excessive daytime sleepiness. Untreated sleep apnea can also increase the risk of heart disease, stroke, diabetes, and other serious health problems. Every participant underwent blood tests and an overnight sleep study called polysomnography, which is considered the most accurate way to measure sleep quality and diagnose sleep apnea. Higher TSH levels, which often indicate poorer thyroid function, were linked to more severe sleep apnea. The findings nevertheless suggest that doctors should consider screening patients with hypothyroidism for sleep apnea and vice versa.