Short-long sleep latency and associated factors in Japanese junior high school children

Abstract

Subjective sleep latency complexity was analyzed in a sample of Japanese junior high school pupils (n = 643, age 12–15 years). Sleep onset latency (SOL) of less than 10 min (short SOL) represented 42.8% of the study group, and 57.2% SOL more than 10 min (long SOL), without significant gender or grade differences. Short SOL was associated with a significantly lower number of night awakenings, good depth of sleep, better subjective impression of sleep, morning type circadian preference and longer desired sleep length. In addition, a sleep quality score was constructed. Short SOL subjects presented with a significantly (P < 0.001) higher sleep quality score. However, the majority of lifestyle habits (such as eating habits, physical activity, media use, bedtime, and sleep time during schooldays, etc.) did not provide a significant difference in relation to short-long SOL. The influence of short-long SOL is better reflected in sleep-wake variables, with obviously better indices in children with short sleep latency.