Figure 1. NREM 1 sleep time and sleep stage shifts increase when scoring sleep studies using AASM sleep scoring rule 5.C.b.

Figure showing a 60-sec epoch from a polysomnogram done on one of my patients. In the first 30-sec epoch, he is in NREM 2 sleep, then has an arousal (arrow). Because no sleep spindles or K-complexes recur following the arousal, the second epoch is scored as NREM 1 because of AASM scoring rule 5.C.b (p. 26 of the AASM Manual). Rule 5.C.b. has proved useful, increasing the amount and percent time of NREM 1 sleep and sleep stage shifts scored, providing a clinically useful marker of sleep fragmentation. This figure is from my laboratory, no permission needed.