Neuroendocrine evaluation in Kleine-Levin syndrome: evidence of reduced dopaminergic tone during periods of hypersomnolence.

A patient with Kleine-Levin syndrome had polysomnography and neuroendocrinological assays performed during asymptomatic (ASMP) and symptomatic (SMP) 24-hr periods. During the SMP, sleep data revealed poor nocturnal sleep efficiency, increased sleep fragmentation and reduced stages 3, 4 and rapid eye movement (REM). No sleep onset REM episodes were seen. Sleep staging in the ASMP was normal. Blood samples were obtained every 20 min and assayed for thyroid-stimulating hormone (TSH), cortisol (CORT), prolactin (PRL) and growth hormone (GH). Patterns of secretion, 24-hr mean and total integrated concentrations, and mean sleep period time values during the ASMP and SMP were compared. The mean 24-hr level of TSH was increased and GH decreased in the SMP. Comparing sleep period time in the SMP to the ASMP, values for TSH and PRL were increased and GH and CORT were reduced in the SMP. These hormone changes support the hypothesis that reduced hypothalamic dopaminergic tone is present in the SMP compared to the ASMP in Kleine-Levin patients.