PURPOSE: Poor sleep is increasing worldwide but sleep studies, using objective measures, are limited in Africa. Thus, we described the actigraphy-measured sleep characteristics of Nigerian in-school adolescents and the differences in these sleep characteristics in rural versus urban-dwelling adolescents using actigraphy plus a sleep diary. METHODS: This comparative, quantitative study involved 170 adolescents aged 13-19 attending six rural and six urban schools in southwestern Nigeria. Participants wore actiwatches and filled sleep diaries concurrently for one week. We ran a mixed model analysis with each sleep characteristic as a dependent variable in each model and the fixed effects of age, weekday versus weekend, rural versus urban residence, sex, and religion. RESULTS: The adolescents were 54.1 % females with a mean age of 15.6 ± 1.3 years. Overall, adolescents' mean bedtime was 22.50 ± 0.85, mean waketime was 5.73 ± 0.68 and mean total sleep time (TST) was 06.07 ± 0.95 h. On both weekdays and weekends, urban adolescents had significantly later bedtimes, earlier waketimes, shorter time-in-bed (TIB) and TST (all p <
0.05) while rural adolescents had lower sleep efficiency, more frequent awakenings and WASO (all p <
0.05). In mixed-model analyses, older adolescents had later bedtimes (p = 0.035) and shorter TST (p = 0.047), urban adolescents had later bedtimes, earlier wake times, shorter TIB and TST than rural adolescents (all p <
0.05), and on weekdays, all adolescents had earlier bedtimes, waketimes, shorter TIB and TST than on weekends (all p <
0.05). CONCLUSION: Adolescents, especially the urban ones, had insufficient sleep with a catch-up-sleep on weekends. Multipronged interventions, including controlling causes of late bedtimes and delaying school start-times are needed to improve sleep, especially among older and urban adolescents.