The conclusive data indicate that developing children are able to extend their sleep by a significant amount during overnight sleep. Post 5 days of experimental sleep extension (1.5 hours earlier than their normal bedtime) children increased sleep duration by an average of 56 minutes. Sleep onset in the extension condition was 1 hour and 8 minutes earlier compared to the baseline condition. Previous studies have shown a 27-minute increase with a 1-hour earlier bedtime, but this study has a more vivid effect. Longer onset sleep did not cause a significant difference in the time in specific sleep stages. REM theta activity was not significantly reduced as hypothesized at the frontal electrodes. However, REM theta activity was reduced during the sleep extension condition at parietal P3 electrode.
These results as well as Go/No-Go task results can indicate behavioral changes. Inhibitory control was improved in the morning compared to the evening. There was no significant different in inhibitory control between the baseline and sleep extension. This could be due to children having a sufficient amount of sleep or inhibitory control. The task may also not cover all effects that sleep extension has to show significant results (Gruber et al., 2012; Sadeh, Gruber & Raviv, 2003; Vriend et al., 2013).
This sample of children slept a normative amount for the 6-9-year-old age group. The average sleep duration in this study was 10 hours, which could explain why the children may have not benefited from the sleep extension compared to those who sleep less. In previous studies, children slept 8.5-9.5 hours which is why there could have been significant results previously (Gruber et al., 2012). Similarly, children may have already had adequate inhibitor control. The task could have also been too easy not allowing children for room of improvement between sessions to see substantial results.
Some correlations were determined from the conclusive data. REM theta activity was correlated with morning inhibitory control during the baseline condition. This could indicate that shorter sleep may make theta activity more efficient. Meaning, that theta activity causes beneficial behavioral effects for children. Longer sleep causes less stress on the child, so behavior will not improve if the child is already at adequate cognitive levels. Again, there was no significant data in sleep extension for REM theta activity so correlations cannot be determined.
Additional data from our lab indicate that theta activity is elevated in children diagnosed with attention-deficit/hyperactivity disorder (ADHD). High amounts of theta activity are not beneficial to inhibitory control in this sample. Due to this, it is assumed by this study that there is an optima amount of theta activity of sleep extension. Further studies will take place to determine if sleep extension alter theta activity enough to improve inhibitory control in children diagnosed with ADHD.