Chronotype is associated with the timing of the circadian clock and sleep in toddlers.
Simpkin CT, Jenni OG, Carskadon MA, Wright KP, Akacem LD, Garlo KG, LeBourgeois MK. Chronotype is associated with the timing of the circadian clock and sleep in toddlers. J Sleep Res. 2014 Aug; 23(4):397-405.