Evening chronotype is associated with changes in eating behavior, more sleep apnea, and increased stress hormones in short sleeping obese individuals

Abstract

Background: Short sleep duration and decreased sleep quality are emerging risk factors for obesity and its associated morbidities. Chronotype, an attribute that reflects individual preferences in the timing of sleep and other behaviors, is a continuum from morningness to eveningness. The importance of chronotype in relation to obesity is mostly unknown. Evening types tend to have unhealthy eating habits and suffer from psychological problems more frequently than Morning types, thus we hypothesized that eveningness may affect health parameters in a cohort of obese individuals reporting sleeping less than 6.5 hours per night.

Methodology and principal findings: BASELINE DATA FROM OBESE (BMI: 38.5±6.4 kg/m(2)) and short sleeping (5.8±0.8 h/night by actigraphy) participants (n = 119) of the Sleep Extension Study were analyzed (www.ClinicalTrials.gov, identifier NCT00261898). Assessments included the Horne and Ostberg Morningness-Eveningness questionnaire, a three-day dietary intake diary, a 14-day sleep diary, 14 days of actigraphy, and measurements of sleep apnea. Twenty-four hour urinary free cortisol, 24 h urinary norepinephrine and epinephrine levels, morning plasma ACTH and serum cortisol, fasting glucose and insulin, and lipid parameters were determined. Eveningness was associated with eating later in the day on both working and non-working days. Progression towards eveningness was associated with an increase in BMI, resting heart rate, food portion size, and a decrease in the number of eating occasions and HDL-cholesterol. Evening types had overtly higher 24 h urinary epinephrine and morning plasma ACTH levels, and higher morning resting heart rate than Morning types. In addition, Evening types more often had sleep apnea, independent of BMI or neck circumference.

Conclusions: Eveningness was associated with eating later and a tendency towards fewer and larger meals and lower HDL-cholesterol levels. In addition, Evening types had more sleep apnea and higher stress hormones. Thus, eveningness in obese, chronically sleep-deprived individuals compounds the cardiovascular risk associated with obesity.

Figure 1. Sleep characteristics per chronotype.

Horizontal bars represent sleep time as measured by actigraphy. Bedtime (mean±SD) and risetime (mean±SD) on all days combined and separately on non-working days and on work days in Morning (grey bars) and Evening types (black bars). The mid-sleep times (MSTs) (mean±SD) are depicted by open diamonds and compared between chronotypes by t-tests.

Figure 2. Pattern and timing of food intake vs. chronotype score.

Plot of chronotype scores versus the number of eating occasions (A), the portion size (B), and the amount of caloric intake after 20∶00 (C) with a trend line, respectively. N = 113 for all. R², slope, and p-value for the prediction of chronotype score on food intake variables in each plot are calculated from gender-corrected models. Closed circles represent women, open diamonds represent men.

Figure 3. Anthropometrics and HDL-C vs. chronotype score.

Plot of Chronotype scores versus BMI (A), neck circumference (B), and HDL-C (C) with a trend line, respectively. N = 119 for all. R² slope, and p-value for the prediction of chronotype score on variables in each plot are calculated from gender-corrected models. Closed circles represent women, open diamonds represent men.

Figure 4. Stress hormones and heart rate vs. chronotype score.

Chronotype scores on the horizontal axis are regressed against plasma ACTH (n = 118; A), 24 h urinary epinephrine (n = 110; B) and norepinephrine (n = 114; C), and resting heart rate (n = 113; D). R² for the gender-corrected model is reported, and slope and p-value for the prediction of chronotype score on variables in the model are given. Closed circles represent women, open diamonds represent men.