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Sleep Regularity Report

How movement in bedtime and wake time is measured across a week, including the gap between weekdays and weekends, and why the number is a description rather than a score.

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The tool

Describe your own spread

Enter the nights you have, or pull them straight out of a diary you already keep on this device. The report tells you how far apart your own nights sat, in minutes, three different ways. It does not tell you whether that is good.

This describes how much your schedule varies. It does not say whether that variation is a problem, and it will never label you with a condition. Some lives require irregular hours. There is no target score here, no ranking against other people, and nothing in the output is a health assessment.

The form below runs in your browser, so it needs JavaScript to work. The published method further down this page does not need one, and it is the part worth reading first.

Where the nights come from

The diary on this device, or the rows below, or both. Loading from the diary overwrites what is in the rows.

Reads the Fourteen-Day Sleep Diary if you keep one in this browser. It uses the time you tried to sleep and the time of your final waking, and drops any night missing either end rather than guessing at it.

The nights

A week is the minimum the metrics literature calls unbiased, and a fortnight is better. Leave a row blank and it is ignored.

Night 1

Night 2

Night 3

Night 4

Night 5

Night 6

Night 7

Where what you type goes

Nowhere. Everything above runs in this browser, on this device. Restadian never receives what you enter, because nothing here sends it anywhere.

What this tool will not tell you, and why

  • A maximum acceptable night-to-night variation in sleep timing. The National Sleep Foundation panel that reviewed this agreed consistency matters and published no number for how much movement is too much. The metrics that describe regularity are defined differently and do not always agree with each other. The Regularity Report describes your spread and refuses to grade it.

Every number above, and where it came from

Each figure this tool uses is registered in the code with the sentence it was taken from. Open one and you can check the number against the source without taking our word for it.

  1. Windred et al., Measuring sleep regularity: theoretical properties and practical usage of existing metricsSleep · 2021
    The sentence the figure came from
    Currently, however, there is no systematic approach to measuring sleep regularity … StDev and IS required over a week of sleep–wake data for unbiased estimates … [SRI] measures the similarity of an individual’s sleep–wake patterns from one day to the next.
  2. Roenneberg et al., Chronotype and social jetlag: a (self-) critical reviewBiology · 2019
    The sentence the figure came from
    the chronic discrepancy between an individual’s Biological Clock and the Social Clock … SJL = MSF − MSW … negative SJL occurs when midsleep times on workdays are later than those on free days … it may be wise to look at negative and positive SJL separately.
  3. Phillips et al., Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timingScientific Reports · 2017
    The sentence the figure came from
    the percentage probability of an individual being in the same state (asleep vs. awake) at any two time-points 24 h apart, averaged across the study … The index is scaled so that an individual who sleeps and wakes at exactly the same times each day scores 100, whereas an individual who sleeps and wakes at random scores 0.
  4. Chaput et al., The importance of sleep regularity — National Sleep Foundation consensus statementSleep Health · 2023
    The sentence the figure came from
    Consistency of sleep onset and offset timing is important for health, safety, and performance. Nonetheless, when insufficient sleep is obtained during the week/work days, weekend/non-work day catch-up sleep may be beneficial.
  5. Carney et al., The consensus sleep diary: standardizing prospective sleep self-monitoringSleep · 2012
    The sentence the figure came from
    To present an expert consensus, standardized, patient-informed sleep diary … Items deemed essential were included in a Core sleep diary, and those deemed optional were retained for an expanded diary … the core CSD was formatted so that one week of nightly sleep data could be recorded on a single diary page.
The method

What it measures, what it assumes, and where that breaks down

What it measures

Variation in the timing of your sleep, expressed three ways: how much your sleep onset moves from night to night, how much your final waking moves, and how far your free-day timing sits from your work-day timing.

That third figure is the one most people find useful, because it is the gap that most often explains a difficult Sunday night.

What it asks you for

Your sleep and waking times across a week or more. Enter them directly, or load them out of a Fourteen-Day Sleep Diary you already keep in the same browser. A night missing either end is dropped rather than guessed at.

What it gives back

Three views of the same fortnight, shown as a shape rather than a score: where your window sat each night, how wide the spread was, and where the work-day and free-day patterns diverge.

Every figure is a dispersion statistic in minutes, in the unit you entered. Each one is computed around the clock rather than along it, so a bedtime either side of midnight cannot inflate it: 23:30 and 00:30 are an hour apart, not twenty-three.

The report describes. What to do about what it describes, if anything, depends entirely on why your schedule looks the way it does, which the report cannot see.

The assumptions it rests on

  1. Variation is descriptive, not evaluative. The report starts from the position that an irregular schedule is a fact about your circumstances rather than a failing.
  2. The midpoint of sleep is a more stable summary than bedtime alone. Bedtime is noisy; when the whole window shifts, the midpoint captures it more cleanly.
  3. A week is the minimum useful window and a fortnight is better. Anything shorter is mostly noise.

Why there is no single number

Several measures of sleep regularity exist in the research, they are defined differently, and they do not always agree with one another. Windred and colleagues say so directly. Picking one and printing it as the number would be picking a winner in an argument that is still open.

So the report shows the spread three ways and grades none of them: the mean, the earliest and latest, the range and the standard deviation, for sleep onset, final waking and mid-sleep alike. The work-day against free-day difference is Roenneberg’s social jet lag, computed exactly as his review defines it, and it is a subtraction rather than a debt.

One figure is missing on purpose. Nobody has published a maximum acceptable night-to-night variation. The National Sleep Foundation panel that reviewed this agreed consistency matters and named no threshold, so the report will not invent one, and it says as much next to the numbers.

What it does not do

  • It does not label you with a disorder, a syndrome, or a sleep type. No output says or implies that your schedule is disordered, and there is no field in the report a label could live in.
  • It gives you no score out of anything, and no comparison to a population norm.
  • It recommends no target level of regularity, because whether regularity matters independently of sleep duration is still an open question and this page is not going to pretend otherwise.

Limitations

It cannot tell whether your variation is chosen or imposed. A schedule that moves because of a rotating rota and one that moves because Friday nights run late produce identical numbers and call for completely different responses.

It also cannot tell you whether regularity is the thing worth working on in your case. That question is genuinely open, and we have a research brief tracking it rather than an answer.