Daytime sleepiness and BMI exhibit gender and age differences in patients with central disorders of hypersomnolence

Abstract

The aim of the present study was to examine gender and age-specific effects on subjective daytime sleepiness (as measured by the Epworth Sleepiness Scale), body weight and eating behaviour in patients with central disorders of hypersomnolence. Based on the European Narcolepsy Network database, we compared 1035 patients with narcolepsy type I and 505 patients with other central disorders of hypersomnolence ("narcoleptic borderland"), including narcolepsy type II (N = 308) and idiopathic hypersomnia (N = 174), using logistic regression and general linear models. In the entire study population, the Epworth Sleepiness Scale was higher in women (N = 735, mean age = 30 years, mean Epworth Sleepiness Scale = 16.6 ± SD 3.9) than in men (N = 805, mean age = 32 years, mean Epworth Sleepiness Scale = 15.8 ± SD 4.4). In women with narcolepsy type I (N = 475), both Epworth Sleepiness Scale and body mass index increased in parallel with age. In women of the narcoleptic borderland (N = 260), the Epworth Sleepiness Scale markedly peaked in their early 30s, while body mass index only started to rise at that age. This rise in body mass index following the Epworth Sleepiness Scale peak cannot be explained by sleepiness-induced uncontrolled eating, as self-reported uncontrolled eating was negatively associated with the Epworth Sleepiness Scale in this group. We propose that the narcoleptic borderland harbours a unique cluster of women in their fertile years with an unexplored aetiology requiring further investigation towards tailored interventions.

Keywords: excessive daytime sleepiness; hypersomnia; impulsive eating behaviour; obesity; sex.

FIGURE 1

Prevalence of symptoms in narcolepsy type I (NT1) and the narcoleptic borderland (NBL) in women and men (N = 1540) as spider graph. The Epworth Sleepiness Scale (ESS) was scaled to values spanning from 10 (0%) to 20 (100%), body mass index (BMI) was scaled to values spanning from 20 (0%) to 30 (100%).

FIGURE 2

Body mass index (BMI) and daytime sleepiness as a function of age at diagnosis. Overall, BMI (a) and sleepiness (b) increase dependent on time of diagnosis. Red and blue lines and shadows show non‐linear local regression fitting (LOESS) and respective confidence intervals. Black circles show predicted values per patient by linear regression (glm with factors Gender and log2(Age), all factors p < 0.001). Confidence intervals of local regression fitting (red and blue lines and shadows) are always overlapping with the linear regression model (black circles), with the exception of Epworth Sleepiness Scale (ESS) in women of the narcoleptic borderland (NBL). Black vertical lines show cut‐offs for low abundant age ranges (16 and 50 years, respectively). (c and d) Daytime sleepiness and BMI in women with narcolepsy type I (NT1) and of the NBL, respectively. Due to low numbers of patients below 16 and above 50 years at diagnosis, only data between 16 and 50 years are shown. (e and f) Within the NBL, daytime sleepiness and BMI diverge in women with idiopathic hypersomnia (IH), with a peak about 30–40 years, but not in women with narcolepsy type II (NT2). Green and orange lines and shadows show ESS and BMI, respectively (shadows indicate confidence intervals of local smoothing).

FIGURE 3

Associations of uncontrolled eating with body mass index (BMI) (a) and Epworth Sleepiness Scale (ESS) (b). Shown are bar charts with standard error bars for men and women with narcolepsy type I (NT1) and from the narcoleptic borderland (NBL). Significances are indicated for the respective post‐hoc t‐tests (***p < 0.001; **p < 0.01; *p < 0.05; °p < 0.1).