Another approach to address this problem is to investigate if comorbidities of REM intrusion, which might be easier to detect with a questionnaire, are associated with NDE too. In this context, it is interesting that REM sleep abnormalities have been linked to migraine. Thus, recurrent vivid dreams are associated with migraine attacks (Lippman, 1954), migraine attacks often occur during REM sleep (Levitan, 1984), and migraine patients exhibit hallucinations (Lippman, 1951, 1953; Daniel C & Donnet A, 2011), increased REM sleep and prolonged REM sleep latencies (Drake et al., 1990), and they show a significantly increased frequency of dream-enacting behavior (Suzuki et al., 2013). In addition, several studies found an association between migraine and narcolepsy, a disorder involving REM intrusion (Dahmen et al., 1999, 2003; Longstreth et al., 2007; Suzuki et al., 2015; Yang et al., 2017). For example, Yang and colleagues found a consistently higher risk of developing narcolepsy in children with migraine compared to those without, and this risk was particularly high in children with migraine with aura (Yang et al., 2017).