Is it necessary to record sleep?

The severe limitations of conventional sleep staging during sleep apnea are now understood. Microarousals are likely to be the dominant cause of symptoms in sleep apnea, but it has been extremely difficult to quantify them in a way that will predict daytime sleepiness or poor vigilance any better than respiratory indices. It is clear that not all apneas are equal on sleep, differences in the degree of arousal required to end an apnea and open the pharynx may help to explain why some individuals with apnea-plus-hypopnea indices (AHIs) of 15 may be symptomless, whereas others are severely disabled. Use of newer techniques to measure arousals, both cortical and autonomic, may produce a better understanding of how to measure sleep.