A child who is upset and crying is going to be creating cortisol — and adrenaline — which is going to disturb his or her ability to get into deep sleep cycles; any form of emotional upset or stress will have a negative effect on sleep. (sugarspiceandglitter.com)
Mechanism: Enhancing deep sleep cycles via «warming / cooling equilibrium» which are required for more amplified release of growth hormone from the pituitary. (factsonhgh.com)
One of them noticed significant improvement in both the number of times awoken throughout the night, as well as an increased deep sleep cycle. (flippingfifty.com)