Combined and Isolated Effects of Sleep Deprivation and Alcohol Intake on Exercise Performance in Humans.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Combined and Isolated Effects of Sleep Deprivation and Alcohol Intake on Exercise Performance in Humans. (NCT02117193), a randomized na study. The primary outcome is Aerobic Performance.

2. Clinical Question

3. Trial Design

This was a randomized, single-masked crossover study marked as completed. The registry record lists enrollment of 10 and identifies the study population in its official title as healthy males. The study began in 2013-10, and primary completion was recorded as 2015-05. The sponsor was Federal University of Rio Grande do Sul.

A crossover design means participants take part in more than one study condition or sequence, allowing observations from the same participant to contribute to comparisons. In general, this can make within-person comparisons useful because each participant can serve as their own reference. However, the interpretation depends on how conditions are assigned and analyzed, including how order and any lingering effects are handled. The sequence order, washout arrangements, and analysis accounting for repeated observations are not reported in the registry record.

The intervention descriptions refer to alcohol intake and sleep deprivation, including a placebo-intake condition and normal sleep. The primary results are posted as four sequence-level means, each based on 10 participants. The record does not connect the sequence labels in those results to the specific treatment combinations. It therefore does not support confidently assigning an observed sequence difference to alcohol, sleep deprivation, or their combination.

Randomization and single masking are recorded, but details of the randomization process, who was masked, and how masking was maintained are not reported in the registry record. The original sample-size justification and the trial’s planned statistical analysis are also not reported in the registry record. The enrollment count is small relative to the larger planning illustrations derived from the observed results, but those illustrations do not establish what the original design team expected or planned.

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

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 Aerobic Performance, measured over After each sequence, up to 8 hours.

The primary endpoint is aerobic performance assessed through heart rate, reported as a mean in bpm. The registry record defines the measurement as the subject’s heart rate after each sequence, up to 8 hours. Heart rate is a continuous physiological measure, so the posted results describe the average value and its standard deviation for each sequence.

In general, a heart-rate measure can describe the cardiovascular response during or after an exercise assessment. The choice of heart rate as an endpoint gives a numerical outcome that can be compared across study conditions. The registry description does not specify the exercise protocol, the exact timing of measurement within the stated period, whether the reported value is a peak or average over a test, or how multiple measurements were combined. Those details are not reported in the registry record, so the endpoint should be interpreted as the posted mean heart-rate measure rather than as a fully specified exercise-performance protocol.

The four posted sequence means range from 172.0 bpm to 176.0 bpm, with standard deviations ranging from 6.5 to 12.19 bpm. The sequence comparisons use Sequence 1 as the reference. These descriptive results provide an overview of the observed heart-rate values, but do not by themselves identify which component of the study conditions accounts for any differences.

7. Results Posted in the Registry

• Sequence 2: mean 173.00 versus 172.00 on control; difference 1.00 (95% CI -8.47 to 10.47), standardized effect d = 0.09; z-test p = 0.836.
• Sequence 3: mean 175.00 versus 172.00 on control; difference 3.00 (95% CI -5.56 to 11.56), standardized effect d = 0.31; z-test p = 0.492.
• Sequence 4: mean 176.00 versus 172.00 on control; difference 4.00 (95% CI -6.34 to 14.34), standardized effect d = 0.34; z-test p = 0.449.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Hydration Status

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Sequence 2: mean 1.02 versus 1.02 on control; difference 0.00 (95% CI -0.00 to 0.00), standardized effect d = 0.00; z-test p = 1.000.
  • Sequence 3: mean 1.01 versus 1.02 on control; difference -0.00 (95% CI -0.01 to 0.00), standardized effect d = -0.42; z-test p = 0.346.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sequence 2 and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sequence 3 and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes listed in the registry record are hydration status, Profile of Mood States, and breath alcohol. Quantitative results are posted for hydration status, but values for Profile of Mood States and breath alcohol are not reported in the registry record. The available secondary results therefore provide only a partial view of the outcomes named in the record.

Across the posted hydration comparisons, the estimates do not provide a precise signal of a difference. Their uncertainty should be considered alongside the uncertainty in the primary heart-rate comparisons. The secondary results do not resolve the limitations in interpreting the primary sequence comparisons, nor do they establish whether alcohol intake, sleep deprivation, or their combination accounts for a pattern.

In general, secondary outcomes can help describe effects on related physiological or behavioral measures, but they do not substitute for a clearly specified primary analysis. The registry record lists multiple outcomes and reports no analysis entries. It does not describe which secondary hypotheses were planned, whether any outcomes were exploratory, or how multiplicity was addressed. If several outcomes and comparisons are examined, the chance of finding an apparently notable result by chance can increase. Unadjusted secondary results therefore carry less weight than a prespecified, fully described analysis.

The absence of posted values for two listed secondary outcomes also means that the overall secondary-outcome pattern cannot be assessed comprehensively from the registry record. No conclusions about those unreported measures should be inferred from the hydration findings or from the primary endpoint.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Hydration Status
• Profile of Mood States
• Breath Alcohol

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous, and the registry reports a mean and standard deviation for each sequence. A mean describes the average observed heart rate, while the standard deviation describes how spread out individual measurements are around that average. These summaries are useful for describing the results, but they do not show the shape of the observations or whether the data contain unusual values.

What do the mean differences represent?

The mean difference compares a sequence mean with the Sequence 1 mean. A positive estimate means the other sequence’s reported mean is higher; a negative estimate would mean it is lower. For the primary outcome, the posted estimates are 1.0 bpm for Sequence 2, 3.0 bpm for Sequence 3, and 4.0 bpm for Sequence 4, each compared with Sequence 1. These are unadjusted comparisons. They do not separate the contributions of alcohol intake and sleep deprivation because the registry record does not give the condition mapping for sequence numbers or post component-specific estimates.

In general, an unadjusted comparison is not adjusted for other variables or for features of the design unless those are explicitly included. Here, the registry record does not describe a model that accounts for repeated measurements, sequence order, or other covariates. The reported comparisons should therefore not be assumed to be adjusted crossover analyses.

How should the confidence intervals be read?

A confidence interval gives a range of values reasonably compatible with the data under the statistical method used. A narrow interval indicates more precision; a wide interval indicates greater uncertainty. In general, a confidence interval that includes zero does not establish a directional difference in a mean-difference analysis. It also does not prove that the true difference is zero. The primary outcome intervals all include zero and cover values on both sides of it, reflecting limited precision in these comparisons.

The method used to calculate the intervals is not reported in the registry record. As a result, the interval estimates can be read as posted, but their exact statistical assumptions cannot be checked from the record. The original statistical plan, including whether an analysis was paired or adjusted, is not reported in the registry record.

What do the p-values say?

The unadjusted p-value is a measure of how unusual data at least as incompatible with a null hypothesis of no difference would be under that hypothesis and the assumptions of the test. It is not the probability that the null hypothesis is true, nor a measure of the size or importance of an effect. The posted primary comparisons have unadjusted p-values of 0.836, 0.492, and 0.449. Because the analysis plan and test details are not reported in the registry record, these values should be interpreted as the posted unadjusted results rather than as confirmation of a particular model.

General statistical context: a large p-value does not demonstrate equivalence or absence of an effect. Demonstrating equivalence requires a defined equivalence margin and an analysis designed for that purpose. Neither an equivalence margin nor an equivalence analysis is reported in the registry record.

Why does the crossover structure matter?

General statistical context: in a crossover trial, measurements from one participant across different conditions are often correlated. A paired analysis can use that within-person relationship, while an analysis that treats observations as independent may estimate uncertainty differently. The record identifies the design as crossover, but it does not state how participant-level pairing was handled. It also does not report sequence order, washout, or a carryover assessment. These omissions limit evaluation of whether the posted comparisons reflect the design adequately.

The displayed standardized effect values are descriptive standardizations of mean differences using a pooled standard deviation. In general, standardization expresses a mean difference relative to outcome variability, which can aid comparison across measures with different units. It does not replace the original unit-based interpretation, and it does not establish practical importance. The record does not state a threshold for an important standardized effect.

Finally, the sample-size illustrations use the observed effect as a planning reference, with stated fractions of that effect. Those calculations are separate from the trial’s original design rationale, which is not reported in the registry record. Their meaning is prospective and conditional on the listed assumptions, not an assessment of what the completed study was powered to detect.

11. Confidence Intervals and Precision

Precision is limited for the primary comparisons. The estimates are based on 10 participants per sequence result, and the confidence intervals span values both below and above zero. For Sequence 2 versus Sequence 1, the interval is -8.466 to 10.47 bpm; for Sequence 3 versus Sequence 1, it is -5.562 to 11.56 bpm; and for Sequence 4 versus Sequence 1, it is -6.344 to 14.34 bpm. These ranges are wide relative to the point estimates and allow multiple interpretations of the underlying mean differences.

In general, a confidence interval reflects both the observed estimate and its uncertainty under the method used. An interval that includes zero is consistent with no mean difference, but also with differences in either direction. It is not a statement that all values in the interval are equally likely, and it does not establish that values outside the interval are impossible.

The registry record does not report a threshold for a meaningful heart-rate difference. Consequently, it is not possible to judge from the record whether the interval excludes effects that would be considered important. The interval calculation method and treatment of the crossover structure are also not reported in the registry record, which further limits assessment of precision. The estimates should be treated as uncertain descriptive comparisons rather than precise estimates of condition effects.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They assume a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row uses the stated fraction of the observed effect as the effect to detect. The planning illustrations are based on the observed effect, not on the trial’s original design assumptions; those original assumptions are not reported in the registry record.

The 80% power column gives the number of participants per arm that the calculation estimates would be needed for an 80% chance of detecting the selected effect under the stated assumptions. The 90% power column gives the corresponding number per arm for a 90% chance. These are planning targets for a hypothetical study, not counts from the completed study. For example, the primary comparison for Sequence 2 lists 1,831 participants per arm for 80% power and 2,451 per arm for 90% power when planning for 100% of the observed effect. The figures change with the comparison and the assumed effect size.

Rows planning for 75% or 50% of the observed effect use smaller effects than the row based on 100% of the observed effect. Smaller effects need more participants to detect under the same assumptions, so their planning figures are larger. These calculations are sensitive to the observed effect used as a starting point, which is uncertain in a study with a small number of participants. They should be treated as planning illustrations and not as an estimate of the study’s achieved ability to detect an effect. This is not observed power.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 1.000; pooled standard deviation σ = 10.799.
2. n = 2 × (1.96 + 0.842)² × 10.799² / 1.000² = 1,830.6, rounded up to 1,831 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 1                      # observed difference in means
sigma <- 10.798983748483                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2117193)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 1,831 (80% power), 2,451 (90% power)
 75% of observed effect: n per arm = 3,255 (80% power), 4,357 (90% power)
 50% of observed effect: n per arm = 7,323 (80% power), 9,803 (90% power)
power.t.test: 1831.6 
Simulated power at n = 1,831 per arm: 0.800 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary endpoint and three named secondary outcomes, but does not report a statistical analysis plan, a hierarchy of hypotheses, or a procedure for addressing multiple comparisons. The primary outcome includes comparisons of three sequence labels against Sequence 1, and hydration status also has posted comparisons. The posted p-values are unadjusted. Without a stated multiplicity strategy, they should not be interpreted as if they account for the number of outcomes or comparisons examined.

In general, testing many outcomes or contrasts can increase the chance that at least one result appears unusual under a no-effect scenario. A multiplicity adjustment or a prespecified testing hierarchy can address this issue, but the appropriate approach depends on the research questions and analysis plan. Whether any adjustment was used is not reported in the registry record. The record also does not report whether the primary endpoint and contrasts were prespecified in the form shown in the posted results.

The registry identifies the trial as a crossover, but the analysis population and participant-level handling are not described. The record does not report whether all enrolled participants contributed to every sequence result, how incomplete sequences were handled, or whether an intention-to-treat or other analysis population was used. Missing outcome data, exclusions, and reasons for missingness are not reported in the registry record.

In a crossover study, within-participant correlation, treatment order, and potential carryover can affect interpretation. The statistical model, treatment of participant effects, period effects, and any carryover assessment are not reported in the registry record. This does not establish that the analysis omitted these considerations; it means that the registry record does not allow their use to be evaluated. The absence of reported analysis details is particularly relevant when interpreting the uncertainty estimates and unadjusted comparisons.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record lists 10 participants at risk for serious adverse events in each of the four groups: Alcohol Intake + Normal Sleep, Alcohol Intake + Sleep Deprivation, Placebo Intake + Normal Sleep, and Placebo Intake + Sleep Deprivation. No serious adverse events are recorded as affecting participants in any of these groups, and no serious adverse-event terms are listed.

These figures describe the serious adverse events recorded for this study. They do not establish that serious events could not occur, and the small number of participants limits how much can be learned about uncommon events. The death counts are not reported in the registry record.

Serious adverse events should be distinguished from other adverse events. The record separately lists other adverse events, but those are not serious-event counts. Safety findings should be read as a report of events observed and recorded during the study, not as a general estimate of risk beyond this trial.

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

The registry record provides descriptive heart-rate means for four sequences, with unadjusted comparisons against Sequence 1. The estimates are small relative to their broad confidence intervals, and the intervals include zero. The results therefore do not provide a precise estimate of differences among the posted sequence labels.

That interpretation is narrower than a claim about whether alcohol intake or sleep deprivation changes exercise performance. The sequence labels are not mapped to specific treatment combinations in the posted outcome results, and no component-specific or combined-effect analysis is reported. The available comparisons cannot isolate the effect of alcohol, the effect of sleep deprivation, or an interaction between them.

The study is described as randomized and crossover, but the statistical treatment of repeated participant observations is not reported in the registry record. The small enrollment and limited precision further constrain interpretation. The registry does not provide a clinically meaningful threshold for the heart-rate outcome, so the estimates cannot be classified as important or unimportant on that basis.

Likewise, a lack of a clearly separated result is not evidence that conditions are equivalent. Equivalence would require a prespecified margin and a suitable analysis, neither of which is reported in the registry record. The results also should not be generalized beyond the population described in the title without further information about eligibility and participant characteristics.

In practical statistical terms, these posted data show observed sequence means and uncertain differences, not a definitive estimate of the separate or combined effects named in the study title. The registry record is informative about the study’s design labels and recorded outcomes, but missing analysis details and unreported results limit the strength and scope of conclusions.

17. Why This Trial Matters Statistically

This trial is statistically interesting because its central question concerns two exposures that may occur together, while its design is recorded as a randomized crossover. A crossover design can be useful for studying within-person responses, but its value depends on analysis that respects repeated observations and treatment order. The registry record does not report how those features were handled, making the distinction between the design label and the available analysis especially important.

The study also illustrates why a point estimate alone is not enough. The primary sequence means are close together, but the confidence intervals are broad and include values in both directions. A reader who focuses only on the point estimates could overstate what the small dataset establishes. Considering uncertainty makes clear that the posted comparisons are not precise estimates of the underlying differences.

Another statistical issue is attribution. The study title and intervention descriptions concern alcohol intake and sleep deprivation, but the outcome comparisons are presented by sequence number without a reported sequence-to-condition mapping. Without that mapping and a model that estimates the component effects, the observed contrasts cannot answer the more specific causal questions implied by the topic.

The planning illustrations also demonstrate that sample-size calculations depend strongly on the effect selected for planning. Rows based on smaller fractions of the observed effect require larger participant counts under the listed assumptions. Because the observed effects are uncertain and the original design rationale is not reported, these calculations are best understood as conditional planning examples, not as a retrospective verdict on the study.

18. 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 most important trial-specific limitation is that the sequence labels in the posted primary results are not linked to the alcohol and sleep combinations. This prevents direct interpretation of each sequence contrast as a specific intervention effect. The record also does not post estimates that separate the alcohol effect, sleep-deprivation effect, or their combination.

Although the study is identified as a crossover, details needed to assess that design are not reported in the registry record. These include condition order, washout, sequence allocation details, and whether the analysis accounts for within-participant correlation or period effects. Carryover assessment is also not reported. These gaps limit confidence in interpreting the posted unadjusted comparisons and their intervals.

Enrollment was 10, and each sequence result is based on 10 participants. The resulting confidence intervals are broad. The registry does not report participant characteristics beyond the healthy-male description in the official title, the number completing all sequences, or the handling of missing observations. Generalizability and completeness of the outcome data therefore cannot be assessed fully.

The primary endpoint description does not specify the exercise protocol, detailed measurement timing, or how heart-rate values were summarized across the stated period. The original sample-size justification, analysis plan, multiplicity approach, and statistical methods are not reported in the registry record. Two named secondary outcomes have no posted quantitative results. These limitations do not show that such procedures or data did not exist; they mean the registry record does not provide them for evaluation.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Combined and Isolated Effects of Sleep Deprivation and Alcohol Intake on Exercise Performance in Humans. — NCT02117193.
• Registry record last updated 2016-12-21; status last verified 2016-10.
• Results first posted 2016-09-22.
• 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.

22. Record Summary

NCT02117193 is a completed randomized, single-masked crossover study sponsored by Federal University of Rio Grande do Sul. Enrollment was 10; the study began in 2013-10, with primary completion in 2015-05. Its stated focus is the combined and isolated effects of sleep deprivation and alcohol intake on exercise performance in humans.

The primary endpoint is mean heart rate in bpm after each sequence, up to 8 hours. Four sequence means and unadjusted comparisons against Sequence 1 are posted. The confidence intervals are broad and include zero. The registry record also lists hydration status, Profile of Mood States, and breath alcohol as secondary outcomes; quantitative results are posted for hydration status, while results for the other two are not reported in the registry record.

The sequence-to-condition mapping, original sample-size rationale, analysis plan, handling of crossover features, and missing-data approach are not reported in the registry record. The findings are therefore best read as uncertain descriptive sequence comparisons rather than separate estimates of the effects of alcohol intake and sleep deprivation.