Sleep and pre-bedtime activities in New Zealand adolescents: differences by ethnicity

Abstract

Aim: To describe the screen and nonscreen activities adolescents engage in one hour before bedtime and associations with sleep quantity and quality, including differences by ethnic group. Design: Cross-sectional survey. Participants: 4,192 adolescents aged 13-17 years (52% boys); 71% NZ European, 13% Māori, 8% Asian, 6% Pacific, and 2% other ethnic groups. Measures: Participants completed questions about sleep timing, quality (Pittsburgh Sleep Quality Index), and chronotype (Morningness-Eveningness Scale for Children). Seventeen questions captured pre-bedtime activities. Results: Overall, 39% slept less than the recommended hour of sleep (<8 h) and 57% reported poor sleep quality. Asian teenagers reported shorter sleep duration than New Zealand (NZ) Europeans (-45 min [95% CI: -58 to -32]) primarily from later bedtimes (1 hour), with higher odds of long sleep latency, but less disturbed sleep and a more “eveningness” chronotype. Bedtimes were later in Māori and Pacific adolescents (15 and 41 min, respectively) than NZ Europeans. Most screen activities were negatively associated with sleep quantity and quality. For nonscreen activities, snacking and drinking caffeinated beverages and alcohol were significantly associated with shorter sleep (-8, -28, and -20 min, respectively), whereas interacting with family and friends and exercise/sports before bed were associated with longer sleep (P < 0.001). Time with family, exercise, schoolwork, and household chores were all associated with better sleep quality (P < 0.001). Ethnic differences were apparent for several pre-bedtime activities. Discussion: Ethnic differences related to subjective sleep parameters exist in NZ adolescents. Observed variations in sleep patterns and presleep activities suggest that sleep health messages should be tailored for different ethnic groups.