The patient described has features consistent with an REM behavior disorder (RBD) . RBD is a movement disorder associated with loss of REM-related muscle atonia and is characterized by complex, vigorous, and frequently violent dream-enacting behavior during REM sleep, along with lack of REM atonia on a sleep study [13]. During these episodes, it is not uncommon for the person experiencing it to injure themselves or anyone sharing a bed with them. Patients with narcolepsy have been described to have REM sleep motor regulation abnormalities that include REM sleep without atonia, excessive twitching, and periodic leg movements during sleep (PLMS) [14]. Recent studies on narcolepsy show that up to 60 % of patients report RBD symptoms and that 43 % had evidence of RBD during an attended polysomnography [13]. The Innsbruck narcolepsy cohort, for instance, showed REM without atonia was present in most patients (100 %) and RBD in 24 % of patients [15]. Clinical variants include RBD induced or worsened by pharmacological agents, most of them being used to treat cataplexy such as an SSRI, RBD in narcoleptic children de novo and RBD in the context of symptomatic narcolepsy [16].

Patients with narcolepsy with cataplexy being treated with antidepressants have a three-fold higher occurrence of RBD in comparison to antidepressant-naïve patients [17]. In medication induced RBD, the initial appropriate intervention would be to withdraw or change treatment. Treatment available for RBD include clonazepam, melatonin, and sometimes pramipexole; however, there is a lack clinical trials evaluating use specifically for RBD in narcoleptic patients [16]. Recognition and modification of treatment of RBD in patients with narcolepsy is important. However, it should be anticipated that RDB may occur and the family should be educated on creating a safe sleep environment (Table 5.3) to prevent injury. Switching to bupropion could reduce the risk for worsening cataplexy and periodic limb movements of sleep.

The case demonstrates a clinical scenario that was seen after the H1N1 pandemic in 2009. The history and clinical findings are diagnostic of narcolepsy with cataplexy . It is important to differentiate delayed sleep phase disorder (DSPD) in this age group since MSLT findings may falsely lead to a diagnosis of narcolepsy. Delayed sleep phase disorders (DSPD) and insufficient sleep syndromes can demonstrate reduced sleep latency as well as sleep onset REM periods. A careful history, use of a sleep log or actigraphy prior to PSG/MSLT, and thorough evaluation of the PSG for other primary sleep disorders, such as sleep apnea, DSPD, insomnia, or periodic limb movement disorders is critical to accurately diagnosing narcolepsy. This is especially important in the diagnosis of narcolepsy type 2, where there is an absence of cataplexy events to help in distinguishing the diagnosis. A clue to DSPD is delayed sleep latency on the sleep study and reduced sleep latency with possible sleep onset REM in the first nap trial of her MSLT.

Narcolepsy has been seen associated with Pandemrix vaccination (an adjuvanted, influenza pandemic vaccine) and also with infection by influenza virus during the 2009 A (H1N1) influenza pandemic [18]. The vaccine safety surveillance system detected this very rare adverse effect that occurred in less than one out of 10,000 vaccine recipients in subjects receiving AS03 adjuvanted A (H1N1) pandemic vaccine made using the European inactivation/purification protocol [19]. Individuals with HLA-DQB1*0602 allele(s) are considered to be genetically susceptible. In 2010, there was a threefold increase in the number of 17–19 years old in Finland that were affected with narcolepsy with this HLA subtype [20].

The underlying pathophysiology related to the sudden increase in incidence was not well understood until recently. Melen et al. evaluated for risk of H1N1 virus infection contributing to the sudden increase in the incidence of childhood narcolepsy observed in Finland in 2010 and found it to be unlikely [21]. In 2015, Ahmed et al. provided evidence of the relationship of the Pandemrix vaccine to the development of narcolepsy [19]. They demonstrated that a significant proportion of sera from HLA-DQB1*0602 haplotype-positive narcoleptic Finnish patients with a history of Pandemrix vaccination (vaccine-associated narcolepsy) contained antibodies to hypocretin receptor 2 compared to sera from nonnarcoleptic individuals with either 2009 A (H1N1) pandemic influenza infection or history of receiving the Focetria vaccination given in Italy [18]. Influenza vaccines containing the A (H1N1) pdm09 virus strain used in the United States were not associated with an increased risk of narcolepsy [22]. Therefore, Pandremix is no longer available, but other vaccinations appear to be safe even for genetically susceptible patients. Effect of the vaccine on patients with an established diagnosis of narcolepsy is unknown.