Hyper- and hypo-thyroidism are considered as clinical conditions of sleep alterations. At present, however, these clinical reports have never been confirmed by studies providing a structured description of subjective and objective sleep quantity and quality. To this aim, we enrolled 15 patients with naïve overt hyperthyroidism (HYPER), 9 with naïve overt primary hypothyroidism (HYPO) and 15 healthy age-, sex- and BMI-matched control subjects (CS). Clinical conditions or drug therapies known to affect sleep per se were considered as exclusion criteria. In all the subjects sleep quantity and quality were evaluated by: 1) self-reporting questionnaires; 2) wrist actigraphy (Actiwatch, Mini Mitter Co., Inc.; Bend, OR, USA) on three consecutive days in free living conditions. The self-reporting questionnaires revealed a reduction in sleep time and an increase in sleep latency in HYPO versus CS (P<0.01) without alterations in the perceived sleep quality. The actigraphic study, however, did not show differences between HYPO and CS in terms of actual sleep time, actual sleep percentage, assumed sleep, sleep latency, sleep efficiency, fragmentation index and moving time percentage. Unexpectedly, both the questionnaires and the actigraphy failed to reveal differences in sleep quality and quantity between HYPER and CS. Notable, however, in the whole cohort of subjects, positive correlations between fT4 levels and fragmentation index (R+0.542, P<0.01) and moving time percentage (R+0.545, P<0.01) and a negative correlation between fT4 and actual sleep percentage (R −0.560, P<0.01) were found. In conclusion, our preliminary data show that hypothyroidism, but not hyperthyroidism, seems to be associated with some subjective impairment of sleep quantity that, however, is not confirmed by the actigraphic evaluation. The existence of positive correlations between fT4 and some actigraphic parameters still supports some influence of thyroid function on sleep, that, however, seems not to be clinically detectable.
25 - 29 Apr 2009
European Society of Endocrinology