0335 Persistence of Sleep Duration Phenotypes Across Nights of Laboratory and Home Sleep Recording

Vgontzas and colleagues have proposed dividing the population of persons with insomnia disorder into short (< 6 hours/night) and normal (> 6 hours/night) sleep duration phenotypes based on their objective sleep duration as measured by one or more nights of polysomnography (PSG). However, first night effects, homeostatic recovery mechanisms and the site where PSG is conducted may all affect the sleep duration observed on individual PSG nights. The current study evaluated the stability of objective sleep duration phenotyping across multiple laboratory and home-based PSG recordings.

Seventy-six adults (Mage = 51.8±16.5 yrs.; 50% women) with an insomnia disorder underwent a series of three PSG recordings in the sleep lab and three in their homes in a counterbalanced order. Participants chose their own bed and rising times each night to produce results representative of their usual sleep patterns. Participants were classified into short (ISS: TST < 6 hours) and normal (INS: TST > 6 hours) duration phenotypes using the mean sleep times across all nights.

Twenty-eight participants were classified as the ISS phenotype and 48 were classified as the INS phenotype with equal numbers of men and women in each group. A linear mixed models analysis showed only significant main effects for phenotype classification (F = 119.72; p < .0001) and recording night (F = 4.29; p < .025). The ISS mean TST was 326.8 minutes whereas the INS mean TST was 396.8 minutes. Mean TST across both groups was significantly shorter on the first PSG night (Mean = 353.0 min.) across settings than on night 2 (Mean = 372.4 min.). The majority of the ISS group (78.6%) and INS group (77.1%) had TST < 6 hours and TST > 6 hours, respectively, on 4 or more nights of sleep recordings.

ISS and INS sleep duration phenotypes have relative stability in their objective sleep times across nights and recording sites. These findings support the growing literature suggesting the distinctiveness of these subtypes of insomnia disorder.

Funding support from the Department of Veterans Affairs Merit Review Grant Program