IMPACT OF CUMULATIVE SLEEP RESTRICTION ON SLEEP PHYSIOLOGY IN CHILDREN WITH AND WITHOUT ATTENTION-DEFICIT/HYPERACTIVITY DISORDER (ADHD)
The impact of reduced sleep duration on sleep physiology has not been extensively studied in children. Children with attention-deficit/hyperactivity disorder (ADHD) may be particularly vulnerable to sleep loss as many of these children have pre-existing sleep problems. Research has yet to establish a physiological basis for these difficulties. The first aim of this dissertation was to examine the impact of cumulative sleep restriction (CSR) on school-age children (aged 6 to 12 years) by exploring sleep physiology. The second and third aims were to compare sleep physiology between TD children and children with ADHD and determine whether the latter are differentially impacted by CSR. An experimental study was conducted where participants’ time in bed (TIB) was reduced by one hour per night over six nights (Restricted condition) and compared to six nights of scheduled typical sleep (Typical condition). Sleep was recorded in the laboratory using polysomnography (PSG) at the end of each condition period. The following dissertation consists of two manuscripts based on the PSG data collected. The first manuscript investigated changes in sleep architecture and the power spectrum of sleep electroencephalography (EEG). REM sleep was reduced in both groups at the end of the Restricted condition while there were no changes in slow wave activity (SWA). Trends in the data suggested that TD children had a reduction in N1 and maintenance of N2 while children with ADHD had an increase in these stages and greater sigma power during CSR. The second manuscript looked at sleep spindle activity, finding a trend towards a decrease in slow spindle density during CSR across groups, suggesting a homeostatic response to the decreased sleep opportunity. There were no group differences in spindle activity; however, higher hyperactivity across groups was related to faster mean frequency of fast spindles. While sleep did not differ between TD children and children with ADHD, there was evidence that children with ADHD experienced impairment in their homeostatic response to sleep loss. As there were no changes in SWA and only minor changes in sleep spindles, it is likely that the manipulation protocol was too mild to cause the expected homeostatic changes.