Clocks and sleep
Variation in common preschool sleep problems as an early predictor for depression and anxiety symptom severity across time
Diana J. Whalen, Kirsten E. Gilbert, Deanna M. Barch, Joan L. Luby, Andy C. Belden: J Child Psychol Psychiatry. 2017 Feb;58(2):151-159. Epub 2016 Sep 12.