FIG. 56:  Because we had sleep studies results in all of these 10,000 patients, we were able to tell whether oxygen desaturation during sleep contributed to risk of sudden death.  Our findings were that if a patient had a significant fall in oxygen saturation, to ≤78%, there was an almost 2-fold increased risk of sudden cardiac death occurring at any time of day, whether during the night or during the daytime, independent of any other variables.^[39]  In other words, the results of this study document that when there is nighttime oxygen desaturation, this is independently predictive of risk of sudden cardiac death.