The twelve inputs are a self-selected or imported chronotype band; workday and free-day sleep onset and wake times; reported sleep latency and awakenings; last caffeine and exercise timing; a must-wake time; a cognitive-demand window; and an optimization goal. They are self-report snapshots of typical behavior and constraints, not sensor data, sleep stages, circadian biomarkers, diagnoses, or cognitive-test results.
This guide separates observable timing from inferred biology and keeps planning experiments distinct from clinical, occupational, and performance claims.
§I.Read the page in three layers: inputs, transformations, suggestions
The twelve inputs are a self-selected or imported chronotype band; workday and free-day sleep onset and wake times; reported sleep latency and awakenings; last caffeine and exercise timing; a must-wake time; a cognitive-demand window; and an optimization goal. They are self-report snapshots of typical behavior and constraints, not sensor data, sleep stages, circadian biomarkers, diagnoses, or cognitive-test results.
The calculator then applies published concepts plus LifeByLogic-authored mappings. In the current code, Q2–Q5 drive the behavioral score and schedule; Q1 does not alter the schedule when those required times are present. Q8 and Q9 affect their radar axes but not the recommended cutoff or exercise window; Q11 affects only cognitive alignment; Q12 does not change a computed output; and an imported Profile affects only the optional gap. These limits matter because the surrounding copy describes broader personalization. A formula can run consistently without the combined tool, bands, or recommendations having clinical validity. Synthetic-profile testing checks software behavior; it is not validation against people, actigraphy, polysomnography, outcomes, or randomized alternatives.
Ordinary calculation runs in the browser, but 'local' does not mean 'never stored.' Using the explicit save feature writes answers and results to browser storage, and the optional gap reads a previously stored Profile. Interpret privacy claims alongside the action actually chosen and the site's current privacy disclosure.
§II.Audit the assumptions before reading any number
Verify whether the four clock times describe ordinary current weeks. The algorithm assumes a five-workday/two-free-day pattern and treats each pair as typical. Rotating shifts, split sleep, variable rosters, caregiving interruptions, travel, illness, and seasonal changes can make the summary misleading. Confirm that 'sleep onset' is when sleep likely began, not when you entered bed, and that wake time is not confused with getting-out-of-bed time.
The schedule generator uses a 7.5-hour adult default rather than measuring personal sleep need. It treats the must-wake time as a hard constraint and converts a latency category to 7, 15, 30, 65, or 100 minutes. In the current v1.0 code, that latency is subtracted once when calculating displayed sleep onset and again when calculating bedtime, so bed-to-wake time becomes 7.5 hours plus twice the selected latency. Treat an implausibly early result as a calculation issue to inspect, not a biological instruction. The tool is adult-oriented and does not apply age-specific guidance for children or adolescents.
§III.Interpret behavioral chronotype and social jetlag in clock units
The behavioral chronotype calculation begins with sleep-debt-corrected midsleep on free days, an established research concept known as MSFsc. LifeByLogic collects original time questions and then maps the resulting clock time to its own 0–100 morningness display. The underlying midsleep time is interpretable; the 0–100 conversion is an owner-authored linear approximation. It is not a percentile, normed score, biological assay, or diagnosis.
Social jetlag is the absolute difference between reported workday and free-day midsleep. Read the minutes as a description of schedule contrast. The interface's Minimal/Mild/Moderate/High/Severe bands are display conventions, not clinical categories. The Arab meta-analysis found observational associations between social jetlag and adiposity measures; it did not establish the calculator's 30/60/90/120-minute diagnostic or individual-risk thresholds, prove causality, or show that reducing a band improves health.
§IV.Do not mistake the regularity proxy or radar for validated measures
The published Sleep Regularity Index compares sleep/wake state at densely sampled time points across days. The Optimizer does not calculate that measure. Its 'SRI proxy' starts at 100 and subtracts LifeByLogic-authored penalties for social jetlag, workday/free-day duration difference, and reported awakenings. It has no reported convergent validation against the published SRI in the same people. Call it a tool-specific regularity display, not an actigraphy-equivalent SRI.
Do not import an 87 target from Windred and colleagues. Their observational UK Biobank study used one week of accelerometry in predominantly middle-aged and older adults; the sample median was 81.0, and the top four quintiles spanned 71.6–98.5 versus the bottom below 71.6. It did not define 87 as a universal target, and its mortality associations cannot transfer to this proxy. The five radar axes are likewise owner-authored arithmetic summaries. Their shape prioritizes tool recommendations; it does not measure health, cognition, treatment need, or risk.
§V.Treat every schedule window as a starting hypothesis
The suggested schedule is generated from the must-wake time, adult duration default, latency answer, behavioral chronotype mapping, and fixed offsets. The current recommendations do not change in response to the user's reported caffeine time, exercise time, desired cognitive-demand window, optimization goal, or imported Profile. The caffeine cutoff uses a seven-hour buffer; caffeine dose, metabolism, medications, pregnancy, and sensitivity vary. The exercise window is not a rule that exercise outside it is harmful; systematic evidence generally does not show that all evening exercise disrupts sleep, although very vigorous exercise close to bed may affect some people.
The 60-minute wind-down is a generic routine window, not a measured requirement. The two-hour cognitive window is an algorithmic estimate, not a forecast of tomorrow's performance. A 2025 systematic review found no main chronotype effect in most studies and synchrony effects in a subset. Use a suggested window only when it fits sleep need, health, work, caregiving, and safety. Never shorten sleep to hit a peak window.
§VI.Read the biology–behavior gap as a tool-specific comparison
A gap appears only when a stored LifeByLogic Chronotype Profile is available. The tool subtracts its 0–100 behavioral mapping from the Profile's 0–100 result and reports magnitude and direction. That arithmetic can show whether two LifeByLogic outputs point earlier or later, but the units are not externally established percentile points or a validated measure of circadian misalignment.
The Well-Aligned/Mild/Moderate/Severe labels and the cutoffs below 10, 10–19, 20–34, and 35 or more are owner-authored bands. There are no cited clinical norms showing that they mark subclinical or clinical states, health-risk strata, or expected benefit from closing a given number of points. Do not use the gap to diagnose dysfunction, infer metabolic or mood risk, select treatment, or judge whether your biology is correct. Direction can support a question: 'Does my required schedule repeatedly pull sleep earlier or later than my stated preference?'
§VII.Turn one plausible suggestion into a safe experiment
Choose the smallest recommendation that is feasible and low risk: stabilize a wake-time range, move the last caffeine earlier, create a short wind-down cue, or relocate one demanding task. Keep other major changes steady for about one to two ordinary weeks. Record the input behavior, sleep opportunity, estimated sleep, daytime sleepiness, and task-specific functioning in plain units. Do not chase the overall radar shape or treat a higher display score as a health outcome.
Stop if the experiment reduces sleep, increases time awake in bed, worsens mood, or creates unsafe sleepiness. The standard calculator is not designed for rotating shifts, polyphasic schedules, suspected sleep disorders, or individualized light and melatonin treatment. Persistent insomnia, unintended sleep, loud snoring or gasping, severe restlessness, unusual mood or energy change, or drowsy-driving risk belongs in qualified care, regardless of a reassuring result.
The Result Provenance Ledger
LifeByLogic original: Copy only the results you plan to act on. For each, complete all four columns. The ledger prevents a visually precise number from acquiring more authority than its inputs and validation support. This utility is static and non-scoring.
| What the page displayed | What inputs and rule produced it | The narrow question it can support | What it cannot establish |
|---|---|---|---|
| Behavioral chronotype / 0–100 morningness | Four typical sleep times → MSFsc clock time → LifeByLogic linear mapping | Does reported free-day timing, after a debt correction, look relatively earlier or later? | Percentile, internal circadian phase, trait diagnosis, or fixed type |
| Social jetlag minutes and band | Absolute difference between reported workday and free-day midsleep; owner band | How different are these two reported schedule midpoints? | Clinical severity, causation, or personal cardiometabolic risk |
| Regularity proxy / timing radar | Owner penalties from social jetlag, duration difference, and awakenings | Which inputs make the tool describe the schedule as less regular? | Published SRI, actigraphy result, mortality target, or diagnosis |
| Biology–behavior gap | Difference between two LifeByLogic 0–100 mappings | Do the paired outputs point in different timing directions? | Percentile-point distance, clinical misalignment, risk, or treatment benefit |
| Bedtime, caffeine, exercise, wind-down, or cognitive window | Must-wake constraint, 7.5-hour adult default, latency category subtracted in both sleep-onset and bedtime calculations, behavioral chronotype mapping, and fixed offsets | Is this a feasible starting time to test? | Personal sleep need, guaranteed sleep, peak performance, or medical prescription |
Circle one row only. Write: 'For the next __ ordinary days, I will try __ without reducing sleep opportunity. I will observe __ in clock time or concrete functioning. I will stop or seek help if __.' Do not total results or convert observations into a new score.
Common questions, answered carefully
01What does the 0–100 behavioral chronotype score mean?
It is LifeByLogic's linear display mapping of calculated MSFsc clock time. Higher is displayed as more morning-oriented and lower as more evening-oriented. It is not a percentile, normed trait score, clinical scale, or direct measure of melatonin timing.
02Is my social jetlag band a diagnosis or risk level?
No. The minute difference describes two reported midsleep times; the named band is an owner-authored display convention. Population studies associate social jetlag with some outcomes, but they do not turn an individual's band into a diagnosis, causal estimate, or forecast.
03Is the regularity result a real Sleep Regularity Index?
No. The published SRI uses repeated epoch-by-epoch sleep/wake state data across days. This tool uses a custom penalty formula based on a few typical self-reports. It may prompt questions about consistency, but it is not interchangeable with actigraphy-derived SRI.
04Should I aim for a regularity score of 87 or higher?
No validated target of 87 applies to this proxy. The cited Windred study did not set 87 as a universal clinical threshold, and its objectively measured cohort values and mortality associations cannot be transferred to a custom self-report score. Use actual clock-time regularity and functioning instead.
05Is the biology–behavior gap clinically meaningful?
Not as currently validated. It is the difference between two LifeByLogic 0–100 outputs. Its direction may help frame a schedule-fit question, but its units and band cutoffs have no established clinical norms, risk calibration, or proven treatment-response meaning.
06Why does the recommended bedtime seem too early or late?
Check the must-wake time, latency category, typical sleep-time entries, and 7.5-hour adult default. In current v1.0, latency is subtracted in both the sleep-onset and bedtime calculations, which can make bedtime especially early; the imported Profile does not alter the schedule. The generator does not estimate personal sleep need or know caregiving, illness, shifts, travel, or actual sleepability.
07Can shift workers or teenagers use these results?
The standard interpretation is not appropriate for rotating shifts or other patterns that do not fit workday/free-day assumptions. The schedule also uses an adult duration default and is not age-calibrated for adolescents. Those users need context-specific guidance rather than literal adherence to the output.
08When should I ignore the optimizer and seek care?
Seek qualified help for persistent insomnia or excessive sleepiness, unintended sleep, loud snoring or gasping, severe restlessness, major mood or energy change, or impairment despite adequate opportunity. Stop driving or hazardous work when sleepy. A favorable display does not overrule symptoms.
Evidence used for this guide
Each source is used only for the role named below. These sources do not validate the LifeByLogic Sleep-Cognition Optimizer, establish an individual’s sleep need, diagnose a disorder, or prove that one schedule will improve health or performance.
- LifeByLogic. LBL Sleep-Cognition Optimizer — Methodology & Validation, version 1.0. lifebylogic.com. Accessed September 1, 2026. Role: Primary product source for the 12 inputs, formulas, bands, radar, schedule, and stated validation status. Transfer limit: An owner-authored methodology documents intended behavior; it is not independent validation and cannot create clinical norms, percentiles, diagnoses, or outcome evidence.
- Roenneberg T, Wirz-Justice A, Merrow M. Life between clocks: daily temporal patterns of human chronotypes. Journal of Biological Rhythms. 2003. doi.org. Accessed September 1, 2026. Role: Source for MSFsc as a research chronotype operationalization. Transfer limit: The published clock-time construct does not validate LifeByLogic's linear 0–100 mapping, bands, or use as a percentile.
- Wittmann M et al. Social jetlag: misalignment of biological and social time. Chronobiology International. 2006. doi.org. Accessed September 1, 2026. Role: Foundational definition of social jetlag as a midsleep difference. Transfer limit: The construct does not provide the tool's five severity bands, a diagnosis, or individual-risk thresholds.
- Phillips AJK et al. Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timing. Scientific Reports. 2017. doi.org. Accessed September 1, 2026. Role: Source for the published Sleep Regularity Index using repeated sleep/wake-state observations. Transfer limit: The SRI method and student associations do not validate a self-report penalty proxy or its 0–100 interpretation.
- Windred DP et al. Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study. Sleep. 2024. doi.org. Accessed September 1, 2026. Role: Objective SRI distribution and observational mortality association in UK Biobank. Transfer limit: One-week accelerometry in mainly middle-aged and older adults does not establish an 87 target, causality, individual prognosis, or any threshold for the LifeByLogic proxy.
- Arab A et al. Social jetlag and obesity: a systematic review and meta-analysis. Obesity Reviews. 2024. doi.org. Accessed September 1, 2026. Role: Population evidence on social jetlag and adiposity-related measures. Transfer limit: Heterogeneous observational studies do not establish causality, five clinical bands, a 60-minute inflection for diagnosis, or personal risk.
- Watson NF et al. Recommended amount of sleep for a healthy adult. Journal of Clinical Sleep Medicine. 2015. doi.org. Accessed September 1, 2026. Role: Adult population sleep-duration recommendation. Transfer limit: The consensus does not validate a fixed 7.5-hour personal target, apply to children, or replace assessment of individual need and symptoms.
- Drake C et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. 2013. doi.org. Accessed September 1, 2026. Role: Experimental evidence that a substantial caffeine dose can affect sleep even six hours before bed. Transfer limit: A 400 mg laboratory dose and small sample do not establish a universal seven-hour cutoff; dose, metabolism, and sensitivity vary.
- Stutz J, Eiholzer R, Spengler CM. Effects of evening exercise on sleep in healthy participants: a systematic review and meta-analysis. Sports Medicine. 2019. doi.org. Accessed September 1, 2026. Role: Evidence boundary for exercise timing and sleep. Transfer limit: Heterogeneous studies do not validate the calculator's fixed three-to-five-hour exercise window or imply that other timing is harmful.
- Chauhan S et al. Chronotype and synchrony effects in human cognitive performance: a systematic review. Chronobiology International. 2025. doi.org. Accessed September 1, 2026. Role: Best current synthesis for chronotype-related cognitive timing. Transfer limit: Mixed task evidence does not validate a two-hour personal peak window or predict productivity, errors, or cognition.
- American Academy of Sleep Medicine, Sleep Education. Shift Work Disorder. sleepeducation.org. Accessed September 1, 2026. Role: Clinical boundary for standard workday/free-day assumptions and persistent symptoms. Transfer limit: A patient overview cannot diagnose a disorder; an online optimizer cannot rule one in or out.
Editorial transfer rule: guidelines, reviews, experiments, and observational studies transfer only to the claim, population, dose, timing, and setting named. They do not transfer reliability, clinical thresholds, norms, causal effects, treatment efficacy, or outcome prediction to an owner-authored LifeByLogic tool or static utility.