Sleep Diary Averages & Variability Calculator
Enter up to seven nights of time in bed, time to fall asleep, and other awake time. The calculator summarizes the diary without setting a sleep schedule or recommending a bedtime.
Average sleep duration7 h 20 min
- Average awake time in bed
- 0 h 40 min
- Weekly sleep efficiency
- 91.67%
- Sleep duration variability
- 0.00 min
- Sleep efficiency variability
- 0.00 percentage points
- Shortest nightly sleep
- 7 h 20 min
- Longest nightly sleep
- 7 h 20 min
- Sleep duration range
- 0 min
- Seven-night duration trend
- 0.00 min per night
Nightly sleep diary summary
| Night | Time in bed | Awake time | Estimated sleep | Sleep efficiency |
|---|---|---|---|---|
| 1 | 480 | 40 | 440 | 91.67% |
| 2 | 480 | 40 | 440 | 91.67% |
| 3 | 480 | 40 | 440 | 91.67% |
| 4 | 480 | 40 | 440 | 91.67% |
| 5 | 480 | 40 | 440 | 91.67% |
| 6 | 480 | 40 | 440 | 91.67% |
| 7 | 480 | 40 | 440 | 91.67% |
Uses 7 valid nights; omitted nights are not treated as zero sleep.
Inputs are elapsed minutes, so overnight clock changes are outside this calculation.
Identical nightly values correctly produce zero variability and a zero trend.
How to use this calculator
- For each night, enter the elapsed minutes from trying to sleep until getting out of bed.
- Enter the estimated time to fall asleep and all other awake time for that same night.
- Check that awake time does not exceed time in bed, then read the average, efficiency, spread, and trend.
- Use the nightly table to check the diary entries before discussing a pattern with a clinician.
How the sleep diary summary is calculated
For each complete night, the calculator starts with time in bed: the elapsed minutes from trying to sleep to getting out of bed. It adds sleep-onset latency to the other awake time, which includes awakenings during the night and time awake after the final awakening. Estimated sleep duration is what remains.
A_i = L_i + W_i
S_i = B_i - A_i
E_i = 100 x S_i / B_i
- B_i is time in bed for night i.
- L_i is time to first fall asleep, and W_i is all other awake time.
- S_i is estimated sleep duration, and E_i is that night's sleep efficiency.
Average sleep and average awake time are the arithmetic means of the valid nights. Weekly sleep efficiency is different from the average of nightly percentages: it is total estimated sleep divided by total time in bed. This gives longer and shorter nights their appropriate weight.
The variability results use sample standard deviation. For sleep duration, SD = sqrt(sum((S_i - mean(S))^2) / (n - 1)). The efficiency variability uses the same formula with nightly efficiency percentages, and is reported in percentage points. At least two complete nights are needed for either standard deviation. The range is simply the longest estimated sleep minus the shortest.
How the seven-night trend works
The trend is an ordinary least-squares slope of estimated sleep minutes against chronological night number. In compact form, b = sum((x_i - mean(x)) x (S_i - mean(S))) / sum((x_i - mean(x))^2). A positive result means the recorded sleep duration rose by that many minutes per night on average; a negative result means it fell. Missing nights are left out rather than filled with zero or interpolated, while their original night numbers remain in the trend.
Variation can be useful for describing a diary, but it does not say whether a particular pattern is healthy. Identical entries correctly have zero variability and a zero trend. A single unusual night can move a seven-night result substantially, especially when there are few complete entries.
What this calculator leaves out
This is a descriptive record, not a sleep-stage measurement, diagnosis, or treatment plan. It does not account for overnight clock changes, naps unless you deliberately include them consistently in the nightly figures, shift-work timing, illness, travel, caregiving, substances, breathing symptoms, or how rested you felt. Diary estimates can differ from wearable, actigraphy, or polysomnography measurements because they measure and classify sleep differently.
Worked example
Suppose seven nights each have 480 minutes in bed. Their estimated sleep durations are 400, 410, 420, 430, 440, 450, and 460 minutes, after subtracting 80, 70, 60, 50, 40, 30, and 20 awake minutes.
The average sleep duration is 430 minutes, or 7 h 10 min, and average awake time is 50 minutes. Total sleep is 3,010 minutes out of 3,360 minutes in bed, so weekly sleep efficiency is 89.58%. The sample standard deviation of sleep duration is 21.60 minutes, the duration range is 60 minutes, and the fitted trend is +10.00 minutes per night.
Common questions
How is total sleep time calculated from a sleep diary?
Estimated sleep duration is time in bed minus time to fall asleep and all other awake time. Other awake time includes awakenings during the night and time awake after the final awakening before getting up. The result is an estimate based on the diary, not a direct measurement of sleep stages.
What is the difference between average nightly efficiency and aggregate weekly efficiency?
Average nightly efficiency gives every valid night equal weight. Aggregate weekly efficiency divides total estimated sleep across the week by total time in bed, so a longer night contributes more minutes to both parts of the calculation. This calculator reports the aggregate weekly figure.
What does sleep-duration variability mean?
It is the sample standard deviation of the estimated sleep durations from the valid nights. A result of zero means every included night had the same estimated duration; a larger result means the recorded durations were more spread out. It describes the entries but does not identify a cause or diagnose a sleep condition.
Why does the calculator use sample standard deviation?
A short diary is commonly used as a sample of a person's sleep pattern rather than the entire pattern. Dividing by n minus 1 gives the conventional sample standard deviation and avoids understating spread in a small set of nights. At least two valid nights are required.
How many nights should a sleep diary include, and should naps be included?
Seven nights provide a practical one-week summary, but a longer diary can better show recurring schedules and unusual events. Naps are excluded from this nightly estimate unless you choose to include them consistently in the figures. Keep the same recording rule throughout a comparison period.
Can this calculator diagnose insomnia or recommend a bedtime?
No. The results describe the times you entered and do not diagnose insomnia, measure sleep stages, prescribe a sleep window, or generate a target bedtime. Persistent sleep difficulty, severe daytime sleepiness, breathing concerns, or drowsy driving deserve professional evaluation.