Hyperactivity in patients with narcolepsy and idiopathic hypersomnia: an exploratory study.

Introduction: Patients with either Idiopathic Hypersomnia or Narcolepsy demonstrate excessive daytime somnolence (EDS) with resultant inattention mimicking Attention Deficit Hyperactivity Disorder (ADHD). Patients with ADHD also often express sleep problems including EDS. Thus, patients with ADHD and patients with idiopathic hypersomnia or narcolepsy may share inattention and daytime drowsiness as common features. However, it is not known whether EDS patients with idiopathic hypersomnia or narcolepsy also have increased movement (hyperactivity) like ADHD patients, the determination of which is the purpose of this study.

Methods: We studied 12 patients (7 Narcolepsy type 2 and 5 Idiopathic Hypersomnia) with EDS as shown by Multiple Sleep Latency Test which served as the gold standard for entry into the study. Twelve subjects without symptoms of EDS served as the control group. None of the participants had a previous history of ADHD. Each participant underwent a one-hour session laying at 45 degrees with surveys about the need to move and actigraphy as an objective measure of movement.

Results: Sleep-disordered patients with EDS reported more symptoms of inattention and hyperactivity on the ADHD Self-Report Scale. At each of the time points patients with EDS had a clear trend to express the need to move more than controls on the Suggested Immobilization Test (SIT). For the total 60 minutes, a large effect size for the need to move during the SIT test was found between patients and controls (Cohen's d = 0.61, p=0.01). Patients with EDS did not express a need to move more to combat drowsiness than controls, nor did actigraphy show any difference in objective movement between patients and controls during the SIT.

Conclusion: Patients with EDS express inattention and a need to move more than controls. However, hyperactivity was not verified by objective measurement, nor did the EDS patients express a need to move to combat drowsiness more than controls. Thus, a hypothesis to be further tested, is whether narcolepsy and idiopathic hypersomnia may be more a model of the inattentive form of ADHD rather than the combined or inattentive/hyperactive form of ADHD. Further studies are needed to explore the relationship between EDS and hyperactivity.