There are multiple factors. To answer your question, yes, temperature could be a discomfort. What is preferred temperature for you personally, need not be comfortable for the child. The adipose in the child may not be able to tolerate the temperature.
Other than that, there are other factors too like C02 in the room during night could be another disturbing factor for the child. Kindly check all 4 parameters from My Air, check the AQ for the night. Change the AC settings and monitor the child. Use My Air device specifically for the child and monitor the values.