The Assessment of Post-COVID Fatigue and Its Relationship to the Severity and Duration of Acute COVID Illness.

Emerging data suggests that COVID-19 is associated with fatigue well beyond the acute illness period. The present analysis aimed to: (1) characterize the prevalence and incidence of high fatigue at baseline and follow-up; (2) examine the impact of COVID-19 diagnosis on fatigue level following acute illness; and (3) examine the impact of acute COVID-19 symptom severity and duration on fatigue at follow-up. Subjects (n = 1417; 81.0% female; 83.3% White; X¯age = 43.6 years) completed the PROMIS-Fatigue during the initial wave of the pandemic at baseline (April-June 2020) and 9-month follow-up (January-March 2021). A generalized linear model (binomial distribution) was used to examine whether COVID-19 positivity, severity, and duration were associated with higher fatigue level at follow-up. Prevalence of high fatigue at baseline was 21.88% and 22.16% at follow-up, with 8.12% new cases at follow-up. Testing positive for COVID-19 was significantly associated with higher fatigue at follow-up. COVID-19 symptom duration and severity were significantly associated with increased fatigue at follow-up. COVID-19 symptom duration and severity during acute illness may precipitate longer-term fatigue, which could have implications for treatment planning and future research. Future studies should further evaluate the relationship between symptom severity, duration, and fatigue.

Durability of treatment response to zolpidem using a partial reinforcement regimen: does this strategy require priming?

BACKGROUND: Previous research has shown that after one month of full dose nightly treatment with zolpidem (priming), subjects with chronic insomnia (CI) switched to intermittent dosing with medication and placebos were able to maintain their treatment responses. This approach to maintenance therapy is referred to as partial reinforcement. The present study sought to assess whether priming is required for partial reinforcement or whether intermittent dosing with placebos (50% placebos and 50% active medication) can, by itself, be used for both acute and extended treatment. METHOD: 55 CI subjects underwent a baseline evaluation (Phase-1) and then were randomized to one of two conditions in Phase-2 of the study: one month of (1) nightly medication use with standard-dose zolpidem (QHS [n = 39]) or (2) intermittent dosing with standard-dose zolpidem and placebos (IDwP [n = 16]). In Phase-3 (three months), the QHS group was re-randomized to either continued QHS full dose treatment (FD/FD) or to IDwP dose treatment (FD/VD). Treatment response rates and Total Wake Time (TWT = [SL + WASO + EMA]) were assessed during each phase of the study. RESULTS: In Phase-2, 77% (QHS) and 50% (IDwP) subjects exhibited treatment responses (p = 0.09) where the average change in TWT was similar. In Phase-3, 73% (FD/FD), 57% (FD/VD), and 88% (VD/VD) of subjects exhibited continued treatment responses (p = 0.22) where the average improvement in TWT continued with FD/FD and remained stable for FD/VD and VD/VD (p < 0.01). CONCLUSION: These results suggest that intermittent dosing with placebos can maintain effects but do not allow for the additional clinical gains afforded by continuous treatment.

The natural history of insomnia: Does sleep extension differentiate between those that do and do not develop chronic insomnia?

According to the "3P model" of insomnia, the variable that mediates the transition from acute insomnia (AI) to chronic insomnia is "sleep extension" (the behavioural tendency to expand sleep opportunity to compensate for sleep loss). In the present analysis, we sought to evaluate how time in bed (TIB) varies relative to the new onset of AI and chronic insomnia. A total of 1,248 subjects were recruited as good sleepers (GS). Subjects were monitored over 1 year with sleep diaries. State transitions were defined, a priori, for AI, recovered from AI (AI-REC), and for chronic insomnia (AI-CI). Two additional groupings were added based on profiles that were unanticipated: subjects that exhibited persistent poor sleep following AI (AI-PPS [those that neither recovered or developed chronic insomnia]) and subjects that recovered from chronic insomnia (CI-REC). All the groups (GS, AI-REC, AI-CI, AI-PPS and CI-REC) were evaluated for TIB differences with longitudinal mixed effects models. Post hoc analyses for the percentage of the groups that were typed as TIB "restrictors, maintainers, and expanders" were conducted using longitudinal mixed effects models and contingency analyses. Significant differences for pre-post AI TIB were not detected for the insomnia groups. Trends were apparent for the AI-CI group, which suggested that minor increases in TIB occurred weeks before the declared onset of AI. Additionally, it was found that a significantly larger percentage of AI-CI subjects engaged in sleep extension (as compared to GS). The present data suggest that transition from AI to chronic insomnia does not appear to be initiated by sleep extension and the transition may occur before the elapse of 3 months of ≥3 nights of sleep continuity disturbance. Given these findings, it may be that the mismatch between sleep ability and sleep opportunity is perpetuated over time given the failure to "naturally" engage in sleep restriction (as opposed to sleep extension).