Evidence shows that babies who regularly sleep less than 12 hours per 24 hours have poorer cognitive and language development at two years of age than do those babies who get more than 12 hours of sleep. And, night time sleep is more important for cognitive and language development compared to daytime sleep. In addition, babies with sleep-disordered breathing (e.g., mouth breathing, snoring, pauses in breathing) have lower language scores at 2 years of age than do those babies with no sleep-disordered breathing. However, their cognitive development is not affected.1
1Smithson l, Baird T, Tamana SK, Lau A, Mariasine J, Chikuma J, Lefebvre DL, Subbarao P, Becker AB, Turvey ST, Sears MR The CHILD Study Investigators, Beal DS, Pei J, Mandhane PJ. Shorter sleep duration is associated with reduced cognitive development at two years of age. Sleep Medicine 2018, Volume 48, 131 – 139.