Block-Level Deep Sleep Consolidation and Environmental Modifiers in Long COVID with Dysautonomia: A Longitudinal N-of-1 Wearable Study
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Background
Sleep architecture fragmentation is common in Long COVID and dysautonomia, yet the relationship between block-level deep sleep consolidation and next-day functional wellbeing has not been characterized longitudinally in this population. We tested the hypothesis that block-level deep sleep architecture predicts next-day wellness better than aggregate stage duration.
Methods
A prospective N-of-1 longitudinal study was conducted across 78 nights between January 1 and March 25, 2026 using a consumer wearable (Garmin Index Sleep Monitor). Next-day wellbeing was assessed using the Overall Feeling Score (OFS; 0–10 scale). A five-tier Architecture Group (AG) classification operationalized consolidation quality. A custom predictive model (Pendulum v5.2) quantified consolidation through block-level weighting and contextual penalties. Space weather metrics (Kp index, daily electron fluence, Load Score) were correlated with sleep architecture and OFS across same-day and lagged alignments. A secondary hierarchical regression examined illness as an independent covariate across the full dataset.
Results
Architecture Group explained 56.7% of next-day OFS variance (r = 0.753, p < 0.001), compared with 17.0% for total deep sleep duration (r = 0.412) and 4.8% for the Garmin Sleep Score (r = 0.220). Pendulum v5.2 explained 43.0% of variance (r = 0.656). The deep sleep fragmentation phenotype occurred on 25.6% of nights despite adequate total deep sleep. Space weather explained 14.2% of OFS variance through architecture degradation; Load Score at 1-day lag was the strongest space weather predictor (r = −0.328, p = 0.004). A binary illness indicator explained an additional 5.7% of OFS variance beyond architecture and space weather (full-model R² = 55.2%), with a mean illness-night residual of −0.56 (SD = 0.36; 95% CI [−0.72, −0.40]), consistent with immune/viral flares reducing OFS through pathways independent of sleep architecture.
Conclusions
Block-level deep sleep consolidation quality is a substantially stronger predictor of next-day wellbeing than total stage duration in Long COVID with dysautonomia. Space weather constitutes a measurable environmental modifier operating through architecture degradation. Immune and viral flares constitute a significant architecture-independent confound consistent with direct neuroinflammatory effects on functional capacity. This framework may be applicable across conditions where sleep architecture fragmentation plays a pathophysiological role.
Author Summary
Sleep fragmentation is common in Long COVID and dysautonomia, but the relationship between block-level deep sleep consolidation and next-day functional outcome has not been characterized longitudinally. Consumer wearables can capture block-level architecture at ecological scale, yet commercial sleep scores show poor predictive validity in this population. This study demonstrates that deep sleep consolidation quality —not total stage duration—is the dominant predictor of next-day wellbeing in Long COVID with dysautonomia (Architecture Group r = 0.753, explaining 56.7% of variance). Space weather constitutes a measurable environmental modifier operating through architecture degradation via dissociable Kp and electron fluence pathways. The block-level framework and Pendulum Model may generalize to other conditions where ANS dysregulation impairs sleep stage consolidation.
