Key result
Acute insomnia was associated with a significant 1.5-hour delay in circadian acrophase (p=0.013) and increased variability in ultradian rhythms at the 90-minute time scale compared to healthy controls.
Cross-Sectional (n=41)
No
Effect estimate: 1.5 hour delay
Absolute Event Rate: 253% vs 234%
p-value: p=0.013
Data-adaptive techniques like singular spectrum analysis reveal subtle circadian delays and ultradian rhythm fragmentation in acute insomnia that traditional methods may miss.
Suggests circadian assessment in acute insomnia; leaves open whether phase-shifting therapies improve outcomes.
Circadian rhythms become less dominant and less regular with chronic-degenerative disease, such that to accurately assess these pathological conditions it is important to quantify not only periodic characteristics but also more irregular aspects of the corresponding time series. Novel data-adaptive techniques, such as singular spectrum analysis (SSA), allow for the decomposition of experimental time series, in a model-free way, into a trend, quasiperiodic components and noise fluctuations. We compared SSA with the traditional techniques of cosinor analysis and intradaily variability using 1-week continuous actigraphy data in young adults with acute insomnia and healthy age-matched controls. The findings suggest a small but significant delay in circadian components in the subjects with acute insomnia, i.e. a larger acrophase, and alterations in the day-to-day variability of acrophase and amplitude. The power of the ultradian components follows a fractal 1/f power law for controls, whereas for those with acute insomnia this power law breaks down because of an increased variability at the 90min time scale, reminiscent of Kleitman's basic rest-activity (BRAC) cycles. This suggests that for healthy sleepers attention and activity can be sustained at whatever time scale required by circumstances, whereas for those with acute insomnia this capacity may be impaired and these individuals need to rest or switch activities in order to stay focused. Traditional methods of circadian rhythm analysis are unable to detect the more subtle effects of day-to-day variability and ultradian rhythm fragmentation at the specific 90min time scale.
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Fossión et al. (2017) conducted a cross-sectional in Acute insomnia (n=41). Acute insomnia vs. Healthy age-matched controls was evaluated on Mean circadian acrophase (time of day with maximum activity) (1.5 hour delay, p=0.013). Acute insomnia was associated with a significant 1.5-hour delay in circadian acrophase (p=0.013) and increased variability in ultradian rhythms at the 90-minute time scale compared to healthy controls.
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