Night eating and sleep problems in Hong Kong adolescents : a cross-sectional study

Abstract

Background: Night eating or eating late at night, such as having night snacks or late dinner, has gained popularity in recent years. Eating near bedtime has been speculated to affect sleep, but such studies are few. Adequate and good quality sleep are important for both physical and mental health, especially in young people. The present study investigated the association between night eating and sleep problems in adolescents. Methods: The Hong Kong Student Obesity Surveillance (HKSOS) project was a cross-sectional study conducted in 2006/07. 42 secondary schools were randomly selected by stratified cluster sampling and 26618 students aged 12-18 were included after data cleaning. The weekly frequency of night snacks of students was categorized as no (no), 1 to 4 days (occasional) and 5+ days (frequent). Usual dinner time and bed time in school days and non-school days were used for calculating dinner-bed intervals. Intervals of equal to or less than 3 hours were classified as short. They were then grouped as having no short intervals (no), having a short interval on either school days or non-school days, and both school days and non-school days. The dependent variables were sleep problems. Students were also asked if they had difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), early morning awakening (EMA), difficulty breathing during sleep (DBS) and snoring in the previous month. Having either DIS, DMS, or EMA was defined as insomnia. The presence of doctor-diagnosed sleep apnoea was also reported. Logistic regression was then used and school cluster effects were accounted for. Age, sex, socioeconomic status, weight status, psychological status, alcohol drinking and smoking were adjusted for. Adjusted odds ratios (AORs) were reported. Results: Compared with no night snacking, frequent night snacking was associated with sleep apnoea (AOR 2.04, 95% CI 1.30-3.20; P for trend 0.004). In addition, DBS was associated with occasional (1.34, 95% CI 1.12-1.62) and frequent (1.74, 95% CI 1.31-2.31) night snacking. The corresponding AORs of snoring were (1.27, 95% CI 1.10-1.46) and (1.26, 95% CI 1.08-1.48). Moreover, the AORs (95% CI) of sleep apnoea were 1.84 (95% CI 1.14-2.97) for having short dinner-bed intervals on both school days and non-school days. DBS was associated with short dinner-bed intervals on either types of days 1.22 (95% CI 1.02-1.47) and both types of days 1.88 (95% CI 1.55-2.29). The corresponding AORs of snoring were 1.25 (95% CI 1.07-1.46) and 2.06 (95% CI 1.79-2.37). Occasional night snacking was associated with significantly higher risk of DIS (1.12, 1.04-1.22; P for trend 0.004). The AORs of DIS were 0.88 (95% CI 0.81-0.95) for having short dinner-bed intervals on either school days or non-school days and 0.65 (95% CI 0.57-0.74) for both types of days (P for trend <0.001). Conclusions: Night eating (night snacking and short dinner-bed interval) was associated with sleep apnoea, DBS and snoring in Hong Kong adolescents. Future studies are warranted to confirm these novel findings.