Is insomnia a neurophysiological disorder? The role of sleep EEG microstructure

Area of Science:

• Neuroscience
• Sleep Medicine
• Clinical Psychology

Background:

• Insomnia, particularly primary insomnia, often lacks identifiable organ dysfunction, unlike other sleep disorders like sleep-related breathing disorders and periodic limb movement (PLM).
• Objective diagnosis of insomnia has historically been challenging due to the absence of specific biomarkers.
• Previous research has focused on quantifying other sleep disorders using respiratory and motor indexes.

Purpose of the Study:

• To establish an objective diagnostic framework for insomnia.
• To investigate the neurophysiological underpinnings of insomnia.
• To identify objective markers for quantifying insomnia severity.

Main Methods:

• Utilized polysomnography (PSG) to investigate sleep architecture and microstructure.
• Analyzed sleep duration, intensity, continuity, and stability.
• Quantified the cyclic alternating pattern (CAP) rate in relation to insomnia.

Main Results:

• Polysomnography (PSG) findings indicate insomnia results from neurophysiological disturbances impacting sleep regulatory mechanisms.
• Analysis of sleep microstructure revealed that various etiologic factors, including depressive disorders, destabilize sleep.
• An increased cyclic alternating pattern (CAP) rate was identified as a common marker reflecting sleep destabilization in insomnia.

Conclusions:

• Insomnia can be objectively identified through structural alterations in sleep, primarily detected by polysomnography (PSG).
• The neurophysiological disturbance in insomnia is characterized by impaired sleep control mechanisms, evidenced by increased CAP rate.
• Polysomnography (PSG) is confirmed as the gold standard for objective sleep measurement, particularly for diagnosing and quantifying insomnia.