Higher Sleep Duration Predicts Moderately Higher Periods Of Light Sleep for Population

Higher Sleep Duration Predicts Moderately Higher Periods Of Light Sleep for Population

Contents

Variables

A
Sleep Duration 3379
A
Periods of Light Sleep 1114

Categories

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Sleep 111
A
Sleep 111

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High Confidence
Weak Effect Size
Positive Relationship
Population Study
cause image gauge image effect image
Participants reported a 8.3% average increase in Periods of Light Sleep following above average Sleep Duration.

Abstract

Periods of Light Sleep was generally 8% higher than average after 6 hours of Sleep Duration per 7 days.

Aggregated data from 1 study participants suggests with a HIGH degree of confidence (p=0.001, 95% CI 0.003 to 0.737) that Sleep Duration has a moderately positive predictive relationship (R=0.37) with Periods of Light Sleep.

The highest quartile of Periods of Light Sleep measurements were observed following an average 7 hours Sleep Duration.

The lowest quartile of Periods of Light Sleep measurements were observed following an average 6 hours of Sleep Duration.

After an onset delay of 0 seconds, Periods of Light Sleep is typically 2% lower than average over the 7 days following around 6 hours of Sleep Duration Sleep Duration.

Keywords: Sleep Duration, Periods of Light Sleep, N-of-1 trials, real-world evidence, causal inference, observational study

Preliminary: Based on 1 participants. Results may change as more data is collected.

Results

Primary Findings

Analysis of 1,128 paired observations from 1 participants revealed a modest improvement in Periods of Light Sleep following above-average Sleep Duration exposure.

+8.0%
Change from Baseline
Modest effect on Periods of Light Sleep
0.02
Predictor Impact Score
Insufficient evidence for causal relationship

Supporting Statistics

High
Confidence
0.370
Correlation (r)
p = 0.800
Significance
z = 0.61
Effect Magnitude
φ = 1.00
Temporality

What This Means

When participants had above-average Sleep Duration:

  • Periods of Light Sleep increased by 8.0% on average
  • Temporal analysis supports Sleep Duration as the predictor (not the outcome)

Interpreting the Predictor Impact Score

The Predictor Impact Score (PIS) integrates multiple Bradford Hill causal criteria into a single metric. Use this guide to interpret the score:

PIS Range Interpretation Recommended Action
≥ 0.5 Strong evidence High priority for RCT validation
0.3 - 0.5 Moderate evidence Consider for experimental investigation
0.1 - 0.3 Weak evidence Monitor for additional data
< 0.1 Insufficient evidence Low priority; may be noise

Note: PIS is a prioritization heuristic, not proof of causation. High scores indicate relationships worth investigating, not confirmed causal effects. With only 1 participants, these scores are preliminary and will become more reliable as additional data is collected.

Optimal Daily Values (Precision Dosing)

Based on the observed relationship, we can estimate the predictor values associated with the best and worst outcomes. These values enable personalized dosing recommendations.

⚠️ Preliminary Data: With 1 participants and 1,128 observations, these optimal values are preliminary estimates. As more data is collected, precision will improve significantly.

7.3 h
Value Predicting Higher Periods of Light Sleep
Average Sleep Duration when Periods of Light Sleep exceeded its mean
6.4 h
Value Predicting Lower Periods of Light Sleep
Average Sleep Duration when Periods of Light Sleep was below its mean

What This Suggests

Periods of Light Sleep tended to be highest when Sleep Duration was around 7.3 h.

Important: These values reflect correlations, not guaranteed causal effects. Individual responses may vary. Use as a starting point for personal experimentation, not as a definitive prescription. Consult healthcare providers before making treatment decisions.

Population Correlation

Sleep Duration Distribution

Periods of Light Sleep Distribution

Relationship Analysis

Statistical Summary

Relationship Statistics

Property Value
Cause Variable Name Sleep Duration
Effect Variable Name Periods of Light Sleep
Sinn Predictive Coefficient 0.017614594309518
Confidence Level HIGH
Confidence Interval 0.36717060282164
Forward Pearson Predictive Coefficient 0.3702
Critical T Value 1.646
Average Sleep Duration Over Previous 7 days Before ABOVE Average Periods of Light Sleep 7 hours
Average Sleep Duration Over Previous 7 days Before BELOW Average Periods of Light Sleep 6 hours
Duration of Action 7 days
Effect Size moderately positive
Number of Paired Measurements 1128
Optimal Pearson Product 0.23104552497535
P Value 0.001
Statistical Significance 0.8
Strength of Relationship 0.36717060282164
Study Type population
Analysis Performed At 2026-01-04
Number of Participants 1

Sleep Duration Info

Property Value
Variable Name Sleep Duration
Aggregation Method MEAN
Analysis Performed At 2020-10-11
Duration of Action 7 days
Kurtosis 3.1431132810239
Maximum Allowed Value 16 hours
Mean 7 hours
Median 7 hours
Minimum Allowed Value 6 minutes
Number of Aggregate Predictors 3162
Number of Aggregate Outcomes 217
Number of Measurements 43055
Number of Measurements (including those generated by tagged, joined, or child variables) 16052
Public true
Onset Delay 0 seconds
Standard Deviation 1.2204190250991
Unit Hours
User Variables 404
UPC 067981966602
Variable Category Sleep
Variable ID 1867
Variance 2.1855287054824

Periods of Light Sleep Info

Property Value
Variable Name Periods of Light Sleep
Aggregation Method SUM
Analysis Performed At 2022-08-15
Duration of Action 24 hours
Kurtosis 5.1480759328174
Mean 23.759169230769 count
Median 22.980769230769 count
Minimum Allowed Value 1 count
Number of Aggregate Predictors 784
Number of Aggregate Outcomes 330
Number of Measurements 2121
Number of Measurements (including those generated by tagged, joined, or child variables) 2121
Public true
Onset Delay 0 seconds
Standard Deviation 8.318648740628
Unit Count
User Variables 33
Variable Category Sleep
Variable ID 6054546
Variance 77.419075601904

Introduction

Background

Sleep Duration (Sleep) and Periods of Light Sleep (Sleep) are both important factors in understanding human health and well-being. This study investigates the relationship between these two variables using real-world observational data.

Traditional randomized controlled trials (RCTs), while the gold standard for causal inference, are often impractical, expensive, or unethical for studying many health relationships. Aggregated N-of-1 observational studies offer a complementary approach that leverages within-subject comparisons across large populations to identify meaningful patterns.

Research Question

Does Sleep Duration affect Periods of Light Sleep?

Additionally, we seek to determine:

  1. What is the direction and magnitude of any effect?
  2. How confident can we be in this relationship based on the available data?
  3. What are the optimal levels of Sleep Duration for maximizing Periods of Light Sleep?

Study Objective

The objective of this study is to determine the nature of the relationship (if any) between Sleep Duration and Periods of Light Sleep. Additionally, we attempt to determine the Sleep Duration values most likely to produce optimal Periods of Light Sleep values.

Study Overview

This is a population-level observational study using aggregated N-of-1 methodology. By aggregating individual N-of-1 experiments, we can identify population-level patterns while accounting for the substantial individual variation that exists in most health relationships. Effect sizes are reported as percent change from baseline, enabling intuitive interpretation and comparison across different measures.

Full Methodology: Framework for Real-World Evidence-Based Pharmacovigilance: Aggregated N-of-1 Trials for Quantifying Treatment Effects

Discussion

Interpretation of Findings

Participants experienced a 8.0% improvement in Periods of Light Sleep following above-average Sleep Duration exposure. The Predictor Impact Score (PIS) of 0.02 indicates insufficient evidence for a causal relationship.

Statistical Significance

Using a two-tailed t-test with alpha = 0.05, it was determined that the change in Periods of Light Sleep is statistically significant at a 95% confidence interval. The p-value of 0.8000 indicates there is less than a 80.00% probability that this result occurred by chance.

After treatment, a 8.3% increase (2.41 count) from the mean baseline 30.1 count was observed. The relative standard deviation at baseline was 13.2%. The observed change was 0.61 times the standard deviation.

A common rule of thumb considers a change greater than twice the baseline standard deviation on two separate pre-post experiments may be considered significant. This occurrence would have only a 5% likelihood of resulting from random fluctuation (a p-value < 0.05).

T-Test Details
Observed t-value: 10.985
Critical t-value: 1.646

Since t = 10.98 > 1.65, we reject the null hypothesis.

Biological Plausibility

A plausible bio-chemical mechanism between predictor and outcome is critical for interpreting observational findings. This is where human judgment excels beyond statistical analysis.

Community feedback on the biological plausibility of this relationship is still being collected. Consider the known mechanisms by which Sleep Duration might influence Periods of Light Sleep.

Bradford Hill Criteria Assessment

The Bradford Hill criteria provide a framework for assessing causality in observational studies. Our methodology operationalizes six of the nine criteria through the Predictor Impact Score (PIS):

Criterion How Addressed Metric
Strength Effect size magnitude Percent change from baseline (Δ%), z-score
Consistency Cross-participant replication Number of users (N), number of pairs (n)
Temporality Predictor precedes outcome Temporality factor (φ), onset delay (δ > 0)
Biological Gradient Dose-response relationship Gradient coefficient (φgradient)
Plausibility Biological mechanism assessment Community votes on mechanism plausibility
Specificity Category appropriateness Interest factor (finterest)

Predictor Impact Score (PIS)

The PIS integrates multiple Bradford Hill criteria into a composite metric quantifying how reliably a predictor affects an outcome. Higher scores indicate stronger evidence:

Population-Level PIS:

$$\text{PIS}_{\text{agg}} = |r_{\text{forward}}| \cdot w \cdot \phi_{\text{users}} \cdot \phi_{\text{pairs}} \cdot \phi_{\text{change}} \cdot \phi_{\text{gradient}}$$

Where φ-factors are saturation functions approaching 1 as evidence accumulates:

  • φusers = 1 - e-N/10 (user saturation)
  • φpairs = 1 - e-n/nsig (pair saturation)
  • φchange = 1 - e-Δspread/Δsig (effect spread saturation)
  • w = weighted average of plausibility votes

Temporality Assessment

We assess evidence for correct causal direction using the temporality factor:

$$\phi_{\text{temporal}} = \frac{|r_{\text{forward}}|}{|r_{\text{forward}}| + |r_{\text{reverse}}|}$$

Values approaching 1 indicate the predictor precedes the outcome (supporting causation); values near 0.5 suggest ambiguous directionality; values near 0 suggest reverse causation or confounding by indication.

Limitations

As with any observational study, correlation does not prove causation. Key limitations include:

  • Unmeasured confounders: Variables not tracked may influence results
  • Self-selection bias: Health trackers may differ from the general population
  • Measurement error: Self-reported data may contain recall bias
  • Confounding by indication: Sicker individuals may use more treatments

However, within-subject comparison and temporal precedence analysis partially mitigate these limitations. If the relationship is merely coincidental, as participants independently modify their Sleep Duration values, the observed strength will decline over time. Spurious correlations naturally dissipate as more data is collected.

Future Directions

Future research should examine:

  • Subgroup analyses to identify individual differences in response
  • Potential confounders and mediators of the observed relationship
  • Optimal dosing and timing for Sleep Duration
  • Confirmation through prospective or randomized designs
  • Biological mechanisms underlying the observed effects

Conclusion

📊 Preliminary Findings: With 1 participants, these results are based on limited data. Effect sizes and confidence will improve as more participants contribute data. Consider these findings directional rather than definitive.

Above-average Sleep Duration was associated with a 8.0% improvement in Periods of Light Sleep—a modest effect. The Predictor Impact Score of 0.02 indicates this relationship is requiring additional data before conclusions.

Bottom Line: Based on a PIS of 0.02 and a 8.0% effect size, this relationship currently lacks sufficient evidence. Continue monitoring as more data becomes available. Note: These conclusions may strengthen or change direction as more data is collected.

These findings contribute to our understanding of how Sleep Duration may influence Periods of Light Sleep in real-world conditions. While preliminary, these results may inform future research directions. As more participants contribute data, the reliability and precision of these findings will improve substantially.

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Methods

Study Design

This study is based on data donated by 1 participants. Thus, the study design is equivalent to the aggregation of 1 separate n=1 observational natural experiments.

This within-subject design is powerful because it controls for all stable individual characteristics (genetics, baseline health status, socioeconomic factors) that might otherwise confound the relationship between variables.

Data Analysis

Temporal Assumptions

The analysis incorporates temporal assumptions about the relationship between variables:

  • Onset Delay: It was assumed that 0 seconds would pass before a change in Sleep Duration would produce an observable change in Periods of Light Sleep.
  • Duration of Action: It was assumed that Sleep Duration could produce an observable change in Periods of Light Sleep for as much as 7 days after the stimulus event.

Statistical Methods

For each participant, we calculated the Pearson correlation coefficient between Sleep Duration values and subsequent Periods of Light Sleep values. Individual correlations were then aggregated using Fisher's z-transformation to produce a population-level estimate:

Individual Correlation:

$$r_i = \frac{\sum(x_{ij} - \bar{x}_i)(y_{ij} - \bar{y}_i)}{\sqrt{\sum(x_{ij} - \bar{x}_i)^2 \sum(y_{ij} - \bar{y}_i)^2}}$$

Fisher's Z-Transformation:

$$z_i = \frac{1}{2} \ln\left(\frac{1 + r_i}{1 - r_i}\right)$$

Aggregated Correlation:

$$\bar{r} = \tanh(\bar{z}) \quad \text{where} \quad \bar{z} = \frac{1}{N}\sum_{i=1}^{N} z_i$$

Effect Size Calculation

Effect sizes are reported as percent change from baseline. For each participant, we compare the outcome following above-average predictor values to the overall baseline outcome:

$$\Delta\%_{\text{baseline}} = \frac{\bar{O}_{\text{follow-up}} - \bar{O}_{\text{baseline}}}{\bar{O}_{\text{baseline}}} \times 100$$

Effect Magnitude (Z-Score)

To assess effect magnitude relative to natural variability, we calculate the z-score:

$$z = \frac{|\Delta\%_{\text{baseline}}|}{\text{RSD}_{\text{baseline}}}$$

where RSDbaseline is the relative standard deviation of outcome during baseline period

A z-score > 2 indicates statistical significance (p < 0.05), meaning the observed change exceeds typical baseline fluctuation and is unlikely due to random variation.

Statistical Significance

Correlation significance is assessed using a two-tailed t-test:

$$t = \frac{r\sqrt{n-2}}{\sqrt{1-r^2}}$$

We reject the null hypothesis (ρ = 0) at α = 0.05 when |t| exceeds the critical value, providing statistical evidence that the observed relationship is not due to chance.

Data Sources

Sleep Duration data was primarily collected using Fitbit. Fitbit makes activity tracking easy and automatic.

Periods of Light Sleep data was primarily collected using Fitbit. Fitbit makes activity tracking easy and automatic.

Data Quality

Data quality measures were applied to ensure reliable results:

  • Minimum Data Requirement: Only participants with sufficient paired observations were included in the analysis.
  • Outlier Handling: Extreme values were winsorized to reduce the influence of measurement errors.
  • Missing Data: Days with missing values were handled using appropriate filling strategies based on the variable type.
  • Test User Exclusion: Test accounts and invalid users were excluded from all analyses.

Principal Investigator

Program & Methods

Mike P. Sinn
Sinn, M. P.

Designed and implemented data collection, aggregation, causal inference pipeline, and automated study generation framework. Developed the Predictor Impact Score methodology operationalizing Bradford Hill criteria for ranking causal relationships in observational data. When he tells people this at parties, they usually say they have to go check on their car.

Individual study outputs are automated, reproducible, and open to external audit. (Which I would seriously recommend.)

Contact

Cite This Study

APA Format
Sinn, M. P. (2026). Causal Analysis: Does Sleep Duration Affect Periods of Light Sleep?. The Journal of Citizen Science. https://studies.crowdsourcingcures.org/study/cause-1867-effect-6054546-population-study
BibTeX 
@misc{sinn_cause_1867_effect_6054546_population_study_2026,
  author = {Sinn, Mike P.},
  title = {Causal Analysis: Does Sleep Duration Affect Periods of Light Sleep?},
  year = {2026},
  publisher = {The Journal of Citizen Science},
  url = {https://studies.crowdsourcingcures.org/study/cause-1867-effect-6054546-population-study},
  note = {Accessed: January 6, 2026}
}
Chicago/Turabian
Sinn, Mike P. "Causal Analysis: Does Sleep Duration Affect Periods of Light Sleep?." The Journal of Citizen Science. Accessed January 6, 2026. https://studies.crowdsourcingcures.org/study/cause-1867-effect-6054546-population-study.
Harvard
Sinn, M.P., 2026. Causal Analysis: Does Sleep Duration Affect Periods of Light Sleep?. [Aggregated N-of-1 Study] The Journal of Citizen Science. Available at: https://studies.crowdsourcingcures.org/study/cause-1867-effect-6054546-population-study [Accessed January 6, 2026].

Study Type: Aggregated N-of-1 Observational Mega-Study
Evidence Level: Level II (Real-World Evidence)
Methodology: Bradford Hill Criteria with Predictor Impact Score (PIS)

References

This framework was originally developed in 2013 based on the Bradford Hill criteria. Subsequent literature has independently validated similar approaches to causal inference from observational data:

  1. Hill, A.B. (1965). The environment and disease: association or causation? Proceedings of the Royal Society of Medicine, 58(5), 295-300. [Bradford Hill criteria]
  2. Lillie, E.O., et al. (2011). The n-of-1 clinical trial: the ultimate strategy for individualizing medicine? Personalized Medicine, 8(2), 161-173. [N-of-1 methodology]
  3. Pearl, J. (2009). Causality: Models, Reasoning, and Inference . Cambridge University Press. [Causal inference]
  4. Hernán, M.A., & Robins, J.M. (2020). Causal Inference: What If . Chapman & Hall/CRC. [Free textbook]
  5. FDA (2018). Framework for FDA's Real-World Evidence Program . U.S. Food and Drug Administration. [Regulatory context]
  6. Duan, N., et al. (2013). Single-patient (n-of-1) trials: a pragmatic clinical decision methodology . Journal of Clinical Epidemiology, 66(8), S21-S28.
  7. Platt, R., et al. (2018). The FDA Sentinel Initiative—an evolving national resource . New England Journal of Medicine, 379(22), 2091-2093.

This information is for research and educational purposes only, not medical advice. Consult a healthcare provider before making health decisions. Terms of Service

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