How much sleep apnea is too much?

First paragraph (this article has no abstract)

Events of breathing interruption are universally observed during sleep. Togo and colleagues [1], in a study to identify respiratory and movement sleep disorders in chronic fatigue syndrome (CFS) patients with and without fibromyalgia (FM), employed an apnea-hypopnea index (AHI) of 18 events per hour as the normal limit and reported an absence of diagnosable sleep-disordered breathing (SDB). They utilized 18 events per hour as being a threshold 'sufficient to account for excessive daytime sleepiness' and did not report the observed AHI. An institutional task force established five events per hour as the normal AHI limit, based on an ample literature review. The Wisconsin Sleep Cohort Study provides evidence that an AHI ranging from 0.1 to 5 events per hour is enough to increase the risk of developing high blood pressure by 42% [2]. From an AHI of 0.1 to one of 18 events per hour, which cut-off point should be used in FM research? Should it be derived from the emergence of symptoms, from literature reviews, or from hypertension research?