Insights into puberty: the relationship between sleep stages and pulsatile LH secretion

Abstract

Context: During the pubertal transition, LH secretion initially increases only during sleep; however, its relationship to sleep stage is unknown.

Objectives: Our objective was to determine whether the initiation of LH pulses is related to a specific sleep stage in pubertal children.

Design and setting: Frequent blood sampling and polysomnographic studies were performed in a Clinical Research Center.

Subjects: Fourteen studies were performed in nine healthy pubertal children, ages 9.9-15.6 yr.

Interventions: Subjects underwent one to two overnight studies with polysomnography and blood sampling for LH at 10-min intervals.

Results: Alignment of polysomnographic records and LH pulses demonstrated that LH pulses (n = 58) occurred most frequently during slow-wave sleep (SWS) (1.1 pulse/h, n = 30) compared with all other sleep stages or periods of wake after sleep onset (P < 0.001). There was also a significant increase in the amount of SWS in the 15 min preceding and the 5 min following each pulse compared with the amount of SWS seen across the study night (P < 0.01).

Conclusions: During puberty, the majority of LH pulses that occur after sleep onset are preceded by SWS, suggesting that SWS is intimately involved in the complex control of pubertal onset. These studies raise concerns about the potential hormonal repercussions of the increasing prevalence of sleep disturbances in adolescents.

Fig. 1.

Representation of sleep stages [wake, REM, N1, N2, and N3 (SWS), in descending order] and LH values in the nine subjects (studied off CPAP) demonstrates the close association between SWS (highlighted by the vertical gray bars) and LH pulse onset (marked by inverted triangles). Note that alignment of the raw PSG data and LH levels, rather than visual inspection, was used in the statistical analyses to determine the sleep stage associated with the onset of each LH pulse.

Fig. 2.

LH pulse frequency (mean ± sd) was significantly greater (P < 0.001) during SWS (N3) than during any other sleep stage or during periods of wake after sleep onset.

Fig. 3.

There was an increased amount of SWS in the 15 min preceding and the 5 min following each pulse compared with the amount of SWS seen across the study night (shaded bar). *, P < 0.01. The cartoon depicts the typical shape of an LH pulse at its onset. Data represent the average (+1 sd) percent time spent in SWS among all subjects. Comparisons were made using a linear mixed model adjusting for repeated measures in each subject.