In pre-school children, sleep objectively assessed via sleep-EEGs remains stable over 12 months and is related to psychological functioning, but not to cortisol secretion

In pre-schoolers, poor sleep objectively assessed at the age of 5.4 years was associated with poor sleep and psychological difficulties one year later. Data indicate that in pre-schoolers, sleep remains stable over a 12-months-period. Pre-schoolers with poor sleep appear to be at risk for developing further psychological difficulties.