Functional neuroimaging evidence for hyperarousal in insomnia

Am J Psychiatry. 2004 Nov;161(11):2126-8. doi: 10.1176/appi.ajp.161.11.2126.


Objective: The authors investigated the neurobiological basis of poor sleep and daytime fatigue in insomnia.

Method: [(18)F]Fluorodeoxyglucose positron emission tomography was used to assess regional cerebral glucose metabolism of seven patients with insomnia and 20 healthy subjects.

Results: Compared with healthy subjects, patients with insomnia showed greater global cerebral glucose metabolism during sleep and while awake, a smaller decline in relative metabolism from waking to sleep states in wake-promoting regions, and reduced relative metabolism in the prefrontal cortex while awake.

Conclusions: Subjectively disturbed sleep in patients with insomnia is associated with greater brain metabolism. The inability to fall asleep may be related to a failure of arousal mechanisms to decline in activity from waking to sleep states. Further, daytime fatigue may reflect decreased activity in the prefrontal cortex resulting from inefficient sleep.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Arousal / physiology*
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Brain / physiopathology
  • Brain Mapping
  • Electroencephalography
  • Female
  • Fluorodeoxyglucose F18
  • Glucose / metabolism*
  • Humans
  • Male
  • Neural Pathways / physiopathology
  • Positron-Emission Tomography*
  • Prefrontal Cortex / diagnostic imaging
  • Prefrontal Cortex / metabolism
  • Prefrontal Cortex / physiopathology
  • Sleep / physiology
  • Sleep Arousal Disorders / diagnosis
  • Sleep Arousal Disorders / diagnostic imaging
  • Sleep Arousal Disorders / metabolism
  • Sleep Initiation and Maintenance Disorders / diagnostic imaging*
  • Sleep Initiation and Maintenance Disorders / metabolism*
  • Sleep Initiation and Maintenance Disorders / physiopathology
  • Wakefulness / physiology


  • Fluorodeoxyglucose F18
  • Glucose