Which of the following are PSG characteristics of REM behavior disorder?

The defining characteristic of REM behavior disorder (RBD) is the presence of abnormal muscle activity during REM sleep, which is typically marked by muscle atonia (loss of muscle tone). However, in individuals with RBD, this atonia is inhibited or absent, leading to sustained muscle activity, as detected by elevated chin electromyography (EMG) readings. This abnormality can manifest as twitching or even complex motor behaviors while the person remains asleep, which is why sustained chin EMG activity is a key indicator of this disorder during REM sleep (Stage R).

Other options, although potentially relevant to sleep physiology, do not specifically align with the hallmark features of REM behavior disorder. Increased respiratory rate is not a definitive characteristic of RBD and may occur due to various factors unrelated to REM sleep disturbances. Decreased heart rate variability during sleep does not align with the parameters typically monitored in RBD and can be seen in various sleep disorders or conditions not specific to RBD. Prolonged periods of wakefulness during REM sleep also do not characterize RBD, as individuals with the disorder experience REM sleep but with abnormal behaviors, rather than failing to stay asleep. Thus, the sustained chin EMG activity accurately captures the essence of REM behavior disorder characteristics during REM