Cyclic Alternating Patterns in Normal Sleep and Insomnia: Structure and Content Differences

Abstract

This work aims to investigate new markers for the quantitative characterization of insomnia, in the context of sleep microstructure, as expressed by cyclic alternating pattern (CAP) sleep. The study group includes 11 subjects with normal sleep and 10 subjects with diagnosed primary insomnia. Differences between normal sleepers and insomniacs are investigated, in terms of dynamics and content of CAP events. The overall rate of CAP and of different phases is considered. The dynamic in the structure and alternation of CAP events is further studied in different scales by use of wavelet analysis, and calculation of energy/entropy features. The content of CAP events is studied in terms of electroencephalography (EEG) complexity analysis for the different types of events. Statistically significant differences are highlighted, both in structure and content. Besides confirming the increase in CAP rate, main findings regarding the microstructure difference in insomnia include: 1) as regards the deep sleep building phases, more irregular activation-deactivation patterns, with bigger deactivation time, i.e., distance between consecutive activation events, and appearing with higher EEG complexity in deactivation, and 2) a bigger duration of desynchronisation phases, with increased EEG complexity and more irregular patterns. This analysis extends previous findings on the relation between CAPrate increase and sleep instability mechanisms, proposing specific features of CAP that seem to play a role in insomnia (as consistently presented via classification analysis). This opens new perspectives for the understanding of the role of CAP in the quantitative characterization of sleep and its disorders.

Relation between heart beat fluctuations and cyclic alternating pattern during sleep in insomnia patients

“…Results were concordant with obtained in previous analysis [2]. In this, the A3-phases in insomniac patients show the same increasing behavior in the light sleep.…”

“…The three groups considered five subjects, two males and three females, where one sleep polysomnographic recording per subject was provided by the Parma University Sleep Disorders Center [2]. In the Nor group the subjects were healthy with a mean age of 36 years and no sleep complaints.…”

“…Increased CAP (generally, also the number of Aphases increase) itself may indicate unstable sleep and / or sleep disturbance, and can also be used to identify patterns associated with some sleep disorders. A-phases are identified as A1, A2 and A3, and are closely related to the stages of sleep wakefulness and NREM [2].…”

European guideline for the diagnosis and treatment of insomnia

“…Central to this model are results showing that patients with insomnia have increased power in fast electroencephalographic (EEG) frequencies during non‐rapid eye movement sleep. This might also be reflected by an increased cyclic alternating pattern rate (Chouvarda et al ., ). An increased frequency of microarousals during rapid eye movement (REM) sleep, which contributes to the perception of parts of REM sleep as wakefulness, has also been observed in patients with insomnia, relative to normal sleepers (Feige et al ., ; Riemann et al ., ).…”

Automatic Identification of Insomnia Based on Single-Channel EEG Labelled With Sleep Stage Annotations

“…In the clinical practice, clinicians diagnose insomnia through sleep questionnaires, polysomnography (PSG) monitoring of the patients, and the diagnostic criteria for insomnia released by American Academy of Sleep Medicine (AASM) [3], [4]. However, the subjectivity of the sleep questionnaires and the first-night effect of the PSG recordings make the insomnia diagnose a time-consuming, expensive and subjective process, which is unsuitable for home-usage [5], [6].…”