title: Nocturnal and daytime panic attacks--comparison of sleep architecture, heart rate variability, and response to sodium lactate challenge.
abstract: BACKGROUND
  The purpose of this study was to determine if nocturnal panic patients have greater autonomic dysregulation than patients with daytime panic.
  
  
  METHODS
  Three groups were studied: patients who suffer from panic attacks during sleep (n = 12), those who suffer from daytime panic attacks only (n = 12), and control subjects (n = 12). Each subject underwent 24-hour holter monitoring for heart rate variability (HRV), an overnight sleep recording, and sodium lactate challenge during wakefulness.
  
  
  RESULTS
  There was a marked subjective response to the sodium lactate challenge in the panic disorder (PD) patients but not in control subjects. Each group showed changes in HRV in response to sodium lactate challenge. The decrease in HRV measures was more marked in PD patients as a whole than in control subjects. During non-rapid eye movement (REM) sleep the value for total power (TP) was significantly higher in the nocturnal panic patients. The PD patients as a whole had higher values for TP and low-frequency (LF) power during REM sleep than control subjects. There were no significant differences between the two PD groups in sleep architecture. The PD patients as a whole had lower sleep efficiency and less stage 4 sleep than control subjects.
  
  
  CONCLUSIONS
  These findings indicate that there are substantial differences between PD and control subjects in autonomic regulation and that there are small differences between patients with daytime panic attacks and those with sleep-related panic attacks.
authors.affiliation: Department of Psychiatry, Toronto Hospital, ON, Canada.
authors.forename: E P
authors.initials: EP
authors.lastname: Sloan
authors.forename: M
authors.initials: M
authors.lastname: Natarajan
authors.forename: B
authors.initials: B
authors.lastname: Baker
authors.forename: P
authors.initials: P
authors.lastname: Dorian
authors.forename: D
authors.initials: D
authors.lastname: Mironov
authors.forename: A
authors.initials: A
authors.lastname: Barr
authors.forename: D M
authors.initials: DM
authors.lastname: Newman
authors.forename: C M
authors.initials: CM
authors.lastname: Shapiro
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007262:Infusions, Intravenous; D016584:Panic Disorder / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000175:diagnosis* / Q000503:physiopathology; D019354:Sodium Lactate / Q000008:administration & dosage
chemical_list: D019354:Sodium Lactate