Fig. 5

Sleep Pattern Changes before and after menarche within subjects. The boxplots illustrates the sleep pattern changes from year 2 to year 3 among girls who did not experience menarche by year 2 but did by year 3 (N = 1237). Each box represents the interquartile range (IQR) of the data, with the median marked. Outliers are represented as individual points. Results indicate statistically significant later bedtimes (hours), shorter sleep durations (hours), later wake-up times (hours), and increased relative social jetlag (hours) post-menarche, after adjusting for developmental changes (p < .001 for all measures)