A Community-Based Study on the Association Between Insomnia and Hypothalamic-Pituitary-Adrenal Axis: Sex and Pubertal Influences

Context:

The association between insomnia disorder and the hypothalamic-pituitary-adrenal (HPA) axis needs to be explored in both adults and adolescents.

Objectives:

Our objective was to investigate the associations of the HPA axis (via serial salivary cortisol) with insomnia disorder and subjective and objective sleep quality in a community-based study.

Design and Setting:

This was a community-based case-control family study.

Participants:

Participants included 205 adolescents (14.2 ± 2.8 years old, 51.7% females, and 57 with insomnia) and 244 adults (46.4 ± 4.1 years old, 52.8% females, and 69 with insomnia).

Main Outcome Measures:

Outcome measures included a diagnostic interview for assessment of insomnia disorder, 3-day actigraphy and sleep diary, and serial salivary cortisol measurement.

Results:

Adults with insomnia had a significantly greater cortisol awakening response (CAR) reference to increase (CAR_i) but a comparable CAR reference to ground and a comparable cortisol level during afternoon and evening when compared with noninsomniac adults. The association between insomnia disorder and larger CAR_i was also found in adolescents at late/post puberty but not in pre/early pubertal adolescents. There was an interaction effect between sex and insomnia disorder on CAR_i level with adult females having larger CAR_i than adult males. Among subjects with insomnia disorder, those with lower subjective sleep efficiency had higher cortisol levels in the late evening (10:00 pm) in both adults and adolescents.

Conclusions:

Our study suggests that a series of insomniac indices at both syndromal and symptomatic levels including clinical diagnosis and poor sleep quality are associated with dysfunction of the HPA axis. The association between insomnia and increased CAR_i emerges at late puberty, and the sex difference in this association occurs in adulthood but not in adolescence.