Do sleep-deprived EEG recordings reflect spike index as found in full-night EEG recordings?

The sleep EEGs of many children with neurodevelopmental disorders reveal epileptiform activity. The aim of this study was to compare spike index (SI) in full-night recordings with SI in sleep-deprived EEGs in the morning; EEGs were obtained over 24 hours using ambulatory equipment. Sixteen children between the ages of 7 and 12 years were included in the study. They had to wake up at 3:00 AM and go to sleep again at 7:30 AM. Epileptiform activity was quantified, and SIs of full-night and morning recordings were compared. Two patients did not fall asleep. In one recording there was a technical problem that made calculations impossible. SIs calculated from EEGs obtained during a short nap in the morning were comparable to those calculated from full-night recordings. There seems to be a higher failure rate during morning recordings because of patients not falling asleep.