Spindle Oscillations in Sleep Disorders: A Systematic Review

Area of Science:

• Neuroscience
• Sleep Medicine
• Biomedical Engineering

Background:

• Sleep microarchitecture and neural oscillations, particularly sleep spindles, are key metrics for quantifying electroencephalogram (EEG) sleep activity.
• While research on sleep spindles in adults with sleep disorders is growing, comprehensive reviews are lacking.

Purpose of the Study:

• To critically review experimental studies investigating sleep spindle activity in adults with and without various sleep disorders.
• To synthesize findings across different sleep disorder categories and identify trends or inconsistencies.

Main Methods:

• A systematic methodology with a priori criteria was employed to retrieve and select relevant articles.
• Thirty-seven studies were reviewed and categorized based on sleep disorder type: insomnia, hypersomnias, and sleep-related movement disorders (including parasomnias).
• All included studies were cross-sectional in design.

Main Results:

• Studies focusing on insomnia and sleep-disordered breathing were more prevalent.
• Findings regarding sleep spindle activity differences between clinical and non-clinical groups were largely inconsistent, with some studies reporting increased, decreased, or no significant differences.
• Significant variability was observed in sample characteristics and analytical methods, including spindle bandwidth, detection techniques, and spectral power calculations.

Conclusions:

• The heterogeneity in study methodologies and findings highlights a critical need for increased research standardization and the adoption of event-based detection methods for sleep spindle analysis.
• Further research is required to clarify the role of sleep spindles in various sleep disorders and their clinical implications.