Physical activity: a safe step toward better quality of life in narcolepsy

There are many reasons why the majority of the general population, including patients with narcolepsy, needs more physical activity. Insufficient physical activity is a significant risk factor for cardiovascular morbidity and mortality, reaching the magnitude of smoking in some studies [1, 2]. In addition to hard endpoints (mortality), physical activity plays an essential role in mental health [3] and quality of life [4].

As patients with narcolepsy decrease their physical activity due to sleepiness and fear of cataplexy, it is not surprising that they are more frequently obese [5] and have lower cardiovascular fitness [6], which is considered a marker of worse prognosis [7].

Ricordeau et al. addressed this important matter in a study published in this issue of Sleep. They imposed a relatively low-intensity exercise program (light walking and cycling below the first ventilatory threshold) within 6 weeks of a supervised exercise program (only one session out of the 3 weekly sessions was on-site; the remaining two were remote), followed by a self-directed period of 18 weeks, with only one motivational call every 6 weeks [8]. Compared to a standard cardiac rehabilitation program of supervised 36 sessions onsite of at least moderate intensity [9], patients with narcolepsy were exposed to a lower and shorter physical activity regimen. Nevertheless, the program set in the Ricardeau et al. trial led to a significant improvement in several aspects. First, the severity of narcolepsy symptoms declined, and night sleep improved. Moreover, specific cardiometabolic parameters improved. At 6 months, the improvement of narcolepsy symptoms was no longer significant, but patients still had less anxiety and depression and had a more favorable cardiometabolic profile.

From the cardiometabolic perspective, it is essential to note that exercise alone is not so powerful in influencing the lipid spectrum, except for triglycerides, with a modest clinical outcome [10]. On the other hand, it is a potent anti-inflammatory intervention [11]. It is thus not surprising that Ricordeau et al. observed only changes in triglyceride levels and glycemia, as well as a borderline decrease in CRP levels. A longer duration and higher intensity would be needed to see larger clinical effects.

But what did patients like about the regular exercise program? We can speculate that they appreciated improvements in mental health, lower depression and anxiety scores, and better attention. These outcomes may be included in so-called patient-related outcome measures (PROMS), which reflect patients’ will and preferences [12].

The intensity of the intervention was not high enough to increase the maximal oxygen consumption in the Ricordeau et al. cohort. In our earlier study, we employed a higher intensity, as indicated by the rating of perceived exertion by Borg, aiming for a level of 13–14, i.e. moderate intensity. Such exercise intensity led to a significant increase in VO_2peak after 3 months, but at the cost of a lower completion rate—only 18 patients out of 48 completed the program [13]. This documents that the motivation to participate in a long-term exercise program is probably not based primarily on rational performance goals.

Relocating exercise programs closer to patients’ homes could improve adherence rates. In the study by Ricordeau et al., once the patients entered the program, the completion rate was high (more than 80% of patients completed the program). Nevertheless, it is worth noting that only 28% of the 106 patients screened were recruited. Eighteen patients did not meet the inclusion criteria; however, more than half (n = 58) refused to participate, primarily due to transportation issues and a lack of time. According to our experience, shorter transportation distance obviously increases the willingness to participate [13].

A large-scale randomized trial is needed for robust data; however, in the meantime, we can confidently trust Ricordeau et al. that supervised physical activity in narcolepsy is feasible, safe, and beneficial for sedentary narcolepsy patients. Similar programs should be offered in person and online by fitness centers and patient organizations and should be recommended by treating physicians.

Disclosure statement

Financial disclosure: The authors have nothing to disclose.

Non-financial disclosure: The authors have no conflicts of interest. Outside the topic of the current editorial, KŠ serves on the advisory board for Eli Lilly.