Description:
<jats:title>Summary</jats:title><jats:p>Hypocretin/orexin signalling varies among sleep–wake behaviours, impacts upon cardiovascular autonomic control and is impaired in patients with narcolepsy with cataplexy (<jats:styled-content style="fixed-case">NC</jats:styled-content>). However, evidence concerning disturbed cardiovascular autonomic control in <jats:styled-content style="fixed-case">NC</jats:styled-content> patients is contrasting, and limited mainly to waking behaviour. We thus investigated whether control of cardiovascular variability is altered in <jats:styled-content style="fixed-case">NC</jats:styled-content> patients during wakefulness preceding sleep, light (1–2) and deep (3–4) stages of non‐rapid eye movement (<jats:styled-content style="fixed-case">NREM</jats:styled-content>) sleep and rapid eye movement (<jats:styled-content style="fixed-case">REM</jats:styled-content>) sleep. Polysomnographic recordings and finger blood pressure measurements were performed on nine drug‐free male <jats:styled-content style="fixed-case">NC</jats:styled-content> patients and nine matched healthy control subjects during spontaneous sleep–wake behaviour in a standardized laboratory environment. Indices of autonomic function were computed based on spontaneous fluctuations of systolic blood pressure (<jats:styled-content style="fixed-case">SBP</jats:styled-content>) and heart period (<jats:styled-content style="fixed-case">HP</jats:styled-content>). During wakefulness before sleep, <jats:styled-content style="fixed-case">NC</jats:styled-content> patients showed significant decreases in indices of vagal <jats:styled-content style="fixed-case">HP</jats:styled-content> modulation, cardiac baroreflex sensitivity and amplitude of central autonomic (feed‐forward) cardiac control compared with control subjects. During <jats:styled-content style="fixed-case">NREM</jats:styled-content> sleep, the negative correlation between <jats:styled-content style="fixed-case">HP</jats:styled-content> and subsequent <jats:styled-content style="fixed-case">SBP</jats:styled-content> values was greater in <jats:styled-content style="fixed-case">NC</jats:styled-content> patients than in control subjects, suggesting a greater contribution of central autonomic commands to cardiac control. Collectively, these results provide preliminary evidence that autonomic control of cardiac variability by baroreflex and central autonomic (feed‐forward) mechanisms is altered in <jats:styled-content style="fixed-case">NC</jats:styled-content> patients during spontaneous sleep–wake behaviour, and particularly during wakefulness before sleep.</jats:p>