Poor sleep affects daytime functioning in typically developing and autistic children not complaining of sleep problems: A questionnaire-based and polysomnographic study

This study used empirically validated insomnia diagnostic criteria to compare depression and anxiety in people with insomnia and people not having insomnia. We also explored which specific sleep variables were significantly related to depression and anxiety. Finally, we compared depression and anxiety in (1) different insomnia types, (2) Caucasians and African Americans, and (3) genders. All analyses controlled for health variables, demographics, organic sleep disorders, and symptoms of organic sleep disorders. Cross-sectional and retrospective. Community-based sample (N=772) of at least 50 men and 50 women in each 10-year age bracket from 20 to more than 89 years old. Self-report measures of health, sleep, depression, and anxiety. People with insomnia had greater depression and anxiety levels than people not having insomnia and were 9.82 and 17.35 times as likely to have clinically significant depression and anxiety, respectively. Increased insomnia frequency was related to increased depression and anxiety, and increased number of awakenings was also related to increased depression. These were the only 2 sleep variables significantly related to depression and anxiety. People with combined insomnia (ie, both onset and maintenance insomnia) had greater depression than did people with onset, maintenance, or mixed insomnia. There were no differences between other insomnia types. African Americans were 3.43 and 4.8 times more likely to have clinically significant depression and anxiety than Caucasians, respectively. Women had higher levels of depression than men. These results reaffirm the close relationship of insomnia, depression, and anxiety, after rigorously controlling for other potential explanations for the relationship.

Until recently, the electrophysiological mechanisms involved in strengthening new memories into a more permanent form during sleep have been largely unknown. The sleep spindle is an event in the electroencephalogram (EEG) characterizing Stage 2 sleep. Sleep spindles may reflect, at the electrophysiological level, an ideal mechanism for inducing long-term synaptic changes in the neocortex. Recent evidence suggests the spindle is highly correlated with tests of intellectual ability (e.g.; IQ tests) and may serve as a physiological index of intelligence. Further, spindles increase in number and duration in sleep following new learning and are correlated with performance improvements. Spindle density and sigma (14-16Hz) spectral power have been found to be positively correlated with performance following a daytime nap, and animal studies suggest the spindle is involved in a hippocampal-neocortical dialogue necessary for memory consolidation. The findings reviewed here collectively provide a compelling body of evidence that the function of the sleep spindle is related to intellectual ability and memory consolidation. Copyright © 2010 Elsevier Ltd. All rights reserved.

As considerably more people are diagnosed with an autism spectrum disorder (ASD), interest in the associated behaviours, including sleep problems has increased. This has resulted in a subsequent increase in the research related to the sleep problems occurring in people with an ASD. This article summarizes and evaluates the current literature related to a) the higher prevalence of a sleep problem compared to typically developing children, b) the specific types of sleep problems for people with an ASD, and c) the possible aetiology of sleep problems in the ASDs within a biopsychosocial framework. It is concluded that recent studies confirm that the majority of this population are likely to experience sleep difficulties, with settling issues in children with an ASD the most commonly reported. However, exploration of the types of sleep difficulties and associated aetiological factors in the ASDs is still in its infancy.