Association between anti-thyroid peroxidase antibody and insufficient sleep in euthyroid population

Low sleep quality induces inflammation. Because anti-thyroid peroxidase antibody (TPO-Ab) is an autoantibody that induces inflammation in the thyroid, insufficient sleep may stimulate the production of TPO-Ab. However, the thyroid function is also associated with sleep. Therefore, to evaluate the association between TPO-Ab positivity and insufficient sleep, the target population should be limited to euthyroid individuals whose free triiodothyronine (T3), free thyroxine (T4), and thyroid-stimulating hormone (TSH) are within the normal ranges.

This cross-sectional study recruited 1324 euthyroid individuals who participated in annual health checkups. Insufficient sleep was assessed by using a questionnaire. Individuals with free T3, free T4, and TSH levels within the normal ranges were defined as euthyroid.

Among the study population, 406 had insufficient sleep, and 242 were TPO-Ab-positive. Insufficient sleep was associated with a higher likelihood of TPO-Ab positivity. Sex and age adjusted odd ratios (95 % confidence intervals, p) of TPO-Ab positive for insufficient sleep was 1.47 (1.08, 2.01, p = 0.014). These associations remained unchanged even after further adjustment for free T4 and TSH, status of body mass index, smoking status, drinking status, mental distress, and physical activity; 1.53 (1.11, 2.10, p = 0.009).

Euthyroid individuals with insufficient sleep may be at risk of autoimmune thyroiditis. Although further investigations are necessary, sleep disorder therapy might reduce the risk of the incidence of autoimmune thyroiditis.