Table 4 The associations of gender/birth profiles, sleep variables, and sleep arrangement factors and nighttime sleep duration evaluated by univariate analysis (**p < 0.01, *p < 0.05).

From: Daytime nap and nighttime breastfeeding are associated with toddlers’ nighttime sleep

Sleep-related factors r R2 p value
Gender and birth profiles
Maternal age at birth  − 0.202* 0.041 0.038
Birth order  − 0.184 0.034 0.059
Birth weight  − 0.128 0.016 0.190
Gender  − 0.055 0.003 0.576
Sleep variables
Total sleep duration 0.847** 0.718 0.000
Sleep efficiency 0.794** 0.630 0.000
WASO  − 0.739** 0.546 0.000
Night wakings  − 0.638** 0.408 0.000
Nap duration  − 0.323** 0.104 0.001
Wake time 0.247* 0.061 0.011
Nap onset time 0.237* 0.056 0.015
Sleep onset time  − 0.231* 0.053 0.017
Bed time  − 0.220* 0.048 0.024
Daily variation in sleep onset time  − 0.086 0.007 0.380
Sleep latency  − 0.041 0.002 0.679
Nap end time  − 0.008 0.000 0.933
Daily variation in wake time  − 0.003 0.000 0.979
Sleep arrangement factors
Nighttime breast feeding  − 0.314** 0.098 0.001
Child having own room  − 0.156 0.024 0.111
Putting children to sleep with formula 0.139 0.019 0.154
Co-sleeping with parents  − 0.076 0.006 0.442