Implications of Anesthetics on Sleep Consolidation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Implications of Anesthetics on Sleep Consolidation (NCT04329091), a na phase 4 study. The primary outcome is Perceptual Learning Protocol.

2. Clinical Question

In practical terms, the intended question concerned whether performance on new spoken words changed after training and a period of dexmedetomidine-associated sedation. The protocol description places this question in the context of memory consolidation during sleep, but the registered design does not include a like-for-like control arm from which to estimate a comparative effect. The intended observations therefore cannot establish a treatment contrast even if results had been recorded. Because the registry states that no data were collected, it does not answer whether perceptual learning was retained, whether performance changed over time, or whether EEG spindle measures were associated with learning.

3. Trial Design

NCT04329091 is registered as a PHASE4, single-group study of dexmedetomidine for the condition Sleep. The sponsor is the University of Chicago. Allocation is recorded as NA, and masking is recorded as NONE. The study status is TERMINATED. The registry lists a start date of 2020-10-16 and a primary completion date of 2021-12-20.

The intervention description specifies a 0.5 mcg/kg bolus followed by an infusion of 0.5-0.7 mcg/kg/hr. The infusion was to be titrated up by 0.1 mcg every 1 minute until the subject spontaneously closed their eyes, then continued for 90 minutes. The protocol description says that subjects would complete word-recognition testing before and after sedation. Training used hard-to-understand speech and did not repeat the same words. Testing after sedation was planned in the morning, afternoon and evening, using new spoken words at each time point.

Enrollment is listed as 9, but the primary outcome description states: study terminated, no data was collected. The registry record does not explain the difference between the enrollment listing and that statement, so the enrollment figure should not be interpreted as a count of participants with observed outcome data. One primary outcome is listed, and no analyses are reported. The registry record does not report a comparator arm, a randomization procedure, or masking beyond the NONE entry. Further details about recruitment, participant characteristics, protocol deviations and the reason for termination are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Study terminated, no data was collected.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Perceptual Learning Protocol, measured over 1 day.

The primary outcome is named Perceptual Learning Protocol, with a timeframe of 1 day. It describes testing word recognition on hard-to-understand speech in the morning, training on that speech, and retesting after sedation. At each time point when the protocol was administered, the planned measure was the number of words correctly perceived out of 50. Later testing was to use new spoken words.

This measure was intended to track performance across the learning and retention sequence. Training was described as producing about 20 percentage points of improvement, but this is part of the protocol description and not an observed result from this study. Repeated testing on new words was intended to assess whether learning generalized beyond words heard during training. The endpoint is therefore a performance measure, not a direct measure of memory consolidation or sleep physiology.

The primary outcome description also states that the study was terminated and no data was collected. No observed scores, changes over time, estimates of uncertainty or statistical tests are reported in the registry record. Consequently, the endpoint defines what was intended to be measured, but it does not yield an empirical estimate of perceptual learning in this study.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a planned measurement process, but it does not report an inferential statistical analysis. The distinction matters: an outcome definition explains what investigators intended to observe, while an analysis plan specifies how observations would be summarized and compared. No analysis is reported for this study, and the primary outcome description says that no data was collected.

What does the endpoint measure?

The endpoint is the number of words correctly perceived out of 50 at each administration of the perceptual-learning protocol. In general, a count of correct responses gives a direct summary of performance on a defined task. Repeating the task at different times can describe how performance varies across those occasions. Here, the registry describes morning testing and training, followed by testing after sedation and further tests in the morning, afternoon and evening using new spoken words. It does not report any scores from these assessments.

The description says training produces about 20 percentage points of improvement. That statement belongs to the planned protocol description; it is not a result measured in this study. Nor does the count of words correct directly measure sleep spindles, memory consolidation, or the physiological state induced by the intervention. Those concepts motivate the study, but the endpoint is behavioral task performance.

What can repeated measurements establish?

In general, repeated measurements can show the course of an outcome within the observed participants. They can also help distinguish performance on trained material from performance on new material if the protocol measures both in a specified way. However, measurements taken from the same person are related rather than independent. A valid analysis should account for that relationship if it estimates change across time. The registry record does not report a statistical model, a method for handling within-person correlation, or a plan for summarizing the repeated scores.

There is also no comparator arm listed. In general, an observed difference between two time points within one group does not isolate the cause of that change. Practice, fatigue, elapsed time and other influences may also affect repeated performance. A concurrent comparison can help address some alternative explanations when designed and analyzed appropriately, but the registry record does not describe such a group. Because no outcome data were collected, this study provides no within-group estimate either.

What do confidence intervals and tests ordinarily convey?

In general, a confidence interval describes the uncertainty around an estimate under the assumptions of the chosen method. A narrower interval indicates greater precision for that estimate; it does not by itself establish that an effect is important or free from bias. A statistical test evaluates compatibility between data and a specified null model, given the test assumptions. Neither a confidence interval nor a test can be calculated from a study outcome when the record contains no observations. The registry reports no interval estimates or test results.

The sample-size assumptions recorded for planning illustrations refer to a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of an observed effect. These are assumptions for illustrations, not evidence that this trial used those methods. The recorded design is single-group, and the registry reports no analysis or observed outcome effect. The illustrations should therefore be treated as hypothetical planning calculations rather than as the study's design, observed power, or evidence about precision.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model expects. If a model assumes less variability than the data contain, standard errors can be too small and confidence intervals can be too narrow. This concern can arise with count or response data when participants differ substantially or responses are correlated. It is a general consideration, not a reported feature of this study: the registry contains no outcome data from which to assess variability or over-dispersion.

Likewise, the endpoint has a bounded score because it counts correct words out of 50. In general, the distribution of a bounded score may affect which statistical model is appropriate, particularly if scores cluster near a boundary. No scores are reported, so the score distribution cannot be assessed. The registry does not specify whether the planned analysis would use a model for counts, proportions, repeated measurements, or another approach.

The study description also proposes examining whether the number and quality of sleep spindles correlate with learning gains. In general, an association analysis would require paired spindle and learning measurements and a specified method to quantify their relationship. The registry does not report such measurements, a definition of spindle quality, an association method, or analysis results. The hypothesis alone does not show that a relationship was observed.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome, Perceptual Learning Protocol, and the protocol description includes testing at multiple times. The study summary also states a separate hypothesis about the number and quality of sleep spindles and perceptual learning. These multiple times and scientific questions could create multiple opportunities for statistical testing if data were collected. The registry record does not report how such multiplicity would be handled, whether one time point was designated as the main comparison, or whether the spindle hypothesis was considered confirmatory or exploratory.

No analysis is reported, and the primary outcome description says that no data was collected. Thus, there are no reported endpoint observations to classify as missing, and no reported method for handling missing measurements. The registry does not state whether an analysis population was defined, how participants who discontinued would be treated, or whether any intention-to-treat or per-protocol analysis was planned. These details are not reported in the registry record.

Enrollment is listed as 9, while the outcome description says the study was terminated with no data collected. The registry does not explain this entry or provide participant flow, completion counts, or reasons for termination. The adverse-event record lists zero participants at risk and zero events; without collected study data, those entries cannot establish that no events occurred. The record therefore provides no basis for assessing attrition, missing-data patterns, multiplicity adjustment, or the population actually analyzed.

11. What the Result Does, and Does Not, Mean

The registry record establishes that a study of dexmedetomidine and perceptual learning was registered, that it was designed as a single-group study, and that its status is TERMINATED. It also describes a planned task measuring correct word recognition out of 50 at repeated testing occasions. Most importantly for interpretation, the primary outcome description states that no data was collected. The record therefore contains no observed result about perceptual learning or its retention.

The study hypothesis proposed that gains in perceptual learning after a 90 minute natural sleep nap might also occur after 90 minutes of dexmedetomidine at a sufficient dose to replicate sleep. That is a statement of the intended scientific question. It is not evidence that the intervention produced such a gain, that the anesthetic state replicated sleep, or that the outcome matched an outcome after natural sleep. No natural-sleep comparison arm is listed, and no outcome data are reported.

The registry also proposed that sleep-spindle number and quality might correlate with learning. No spindle measurements, correlation estimates, or related analyses are reported. The hypothesis does not demonstrate an association, and the record cannot establish whether the relevant EEG measures were obtained.

The absence of results does not show that dexmedetomidine changed performance, nor does it show that performance remained unchanged. It also does not establish the presence or absence of adverse events. The zero entries in the adverse-event record are accompanied by zero participants at risk, while the primary outcome description says no data was collected. They should not be read as a safety finding.

In general, an estimate needs observations, a defined analysis and an account of uncertainty to support conclusions about the magnitude and precision of an effect. Those elements are not reported for this study. The enrollment listing of 9 does not supply an outcome estimate or clarify how many participants contributed data. The record can inform readers about the intended design and its termination, but it cannot answer the study's efficacy, association or safety questions.

12. Why This Trial Matters Statistically

This study illustrates why a registered hypothesis, an endpoint definition and an observed result are different kinds of evidence. The registry sets out an interesting measurement question: whether performance on new spoken words would be retained after dexmedetomidine-associated sedation, and whether sleep-spindle features would relate to learning. But a clear question and a defined outcome do not constitute an estimate. The record reports that no data was collected, so there is no statistical result to interpret.

The single-group design is also important to the interpretation. The scientific background discusses natural sleep, but the registry does not list a natural-sleep arm or another concurrent comparator. A comparison described in a rationale or hypothesis is not the same as an implemented control group. This distinction prevents the intended comparison from being mistaken for a result supported by the registered design.

The entry also demonstrates why safety counts need their denominators and data-collection context. Zero events alongside zero participants at risk do not establish an absence of events among treated participants. Registry entries are meaningful only when read alongside the study status and outcome-collection information.

Finally, planning illustrations and observed trial evidence answer different questions. General assumptions about significance level, allocation and effect size can support hypothetical planning, but they do not provide power observed in a completed study or recover missing outcomes. For statistical readers, the most defensible conclusion is therefore about the information available: the record describes an intended study, records termination and reports no collected outcome data. It does not provide evidence for or against the proposed learning or spindle hypotheses.

13. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpretation is that the primary outcome description says no data was collected. This prevents estimation of performance, change over time, uncertainty, or any association with EEG sleep spindles. No analysis results are reported. The registry record does not explain why the study was terminated or whether any procedures were completed before termination.

Enrollment is listed as 9, but participant flow and the meaning of that listing are not explained. It cannot be treated as the number of participants with usable outcome data because the primary outcome entry explicitly reports no data collection. Demographic characteristics, eligibility criteria, recruitment details and reasons for discontinuation are not reported in the registry record.

The study is recorded as single-group, with allocation NA and masking NONE. No comparator arm is listed, although the rationale refers to natural sleep. Without a registered concurrent comparison, the record does not define a direct contrast between dexmedetomidine and natural sleep. The absence of outcome data further means that no within-group trajectory can be assessed.

The registry does not report a statistical analysis plan, handling of repeated measurements, missing-data procedures, multiplicity strategy, analysis population, or a method for assessing the spindle hypothesis. The adverse-event entries list zero participants at risk and zero events, so they do not provide an interpretable safety denominator. These limitations are specific to the information recorded for this study and restrict conclusions to its design, planned endpoint and termination status.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Implications of Anesthetics on Sleep Consolidation — NCT04329091.
• Registry record last updated 2023-02-24; status last verified 2023-02.
• Results first posted 2023-02-24.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

17. Record Summary

NCT04329091 is a University of Chicago PHASE4 study of dexmedetomidine for Sleep. It is recorded as single-group, with allocation NA and masking NONE, and its status is TERMINATED. The registry lists enrollment as 9, a start date of 2020-10-16 and a primary completion date of 2021-12-20.

The planned primary outcome, Perceptual Learning Protocol, measured words correctly perceived out of 50, with a timeframe of 1 day. The intervention description specifies a 0.5 mcg/kg bolus and a 0.5-0.7 mcg/kg/hr infusion, titrated until spontaneous eye closure and continued for 90 minutes. The primary outcome description states that no data was collected. No analyses are reported, and no comparator arm is listed.

The registry record therefore describes the intended question and procedures but does not report outcome estimates, statistical tests, confidence intervals, or interpretable adverse-event results.