If you are using CBT-I in 2026, sleep efficiency is one of the most useful numbers in your sleep diary. It tells you how much of your time in bed is actually being used for sleep.
The simple formula is:
sleep efficiency = time asleep / time in bed × 100
A higher number usually means your sleep is more consolidated. A lower number often means your bed is becoming associated with wakefulness: lying there awake, trying harder, checking the clock, or staying in bed long after the night has already ended.
Sleep efficiency calculator
Enter one sleep diary night. The large number is standard clinical sleep efficiency: estimated total sleep time divided by total time in bed. The smaller Zomni score shows the related app interval for context.
Your sleep diary
Use minutes if you do not know exact clock times.
A useful improvement range — CBT-I watches the trend across several nights.
The Zomni app score uses your core sleep interval, so it can be higher when you were awake during the night. Treat both as educational estimates; CBT-I decisions follow trends and safety context, not one night.
How the calculator works
The calculator uses the standard sleep efficiency formula: estimated total sleep time divided by total time in bed.
It starts with time in bed: the full interval from when you got into bed until when you got out of bed. Then it subtracts three common blocks of non-sleep time:
- Time to fall asleep — sleep latency.
- Awake during the night — wake-after-sleep-onset minutes.
- Time in bed after final awakening — the time you stayed in bed after your last real wake-up.
So the primary result is:
sleep efficiency = (time in bed - time to fall asleep - awake during the night - time after final wake-up) / time in bed × 100
The calculator also shows a related Zomni app score. Zomni iOS estimates the core sleep interval by subtracting sleep latency and time after final wake-up, while brief night wake-ups are tracked separately in the sleep diary. That app score usually runs a little higher than standard sleep efficiency when the night includes wake-after-sleep-onset time.
That is why the calculator shows two numbers:
| Result | What it means |
|---|---|
| Sleep efficiency (standard) | Estimated total sleep time divided by total time in bed. |
| Zomni app score | Mirrors the app's core sleep interval score, with night wake time tracked separately. |
For most people, the two numbers are close. If you wake for long stretches during the night, the standard sleep efficiency score will be lower.
What is a good sleep efficiency score?
CBT-I uses a few practical ranges, and Zomni applies the same bands:
| Sleep efficiency | Range | How to read it |
|---|---|---|
| 90%+ | High | Sleep is well consolidated relative to time in bed. |
| 85–89% | Medium | A useful improvement range, especially if it is stable over several nights. |
| 75–84% | Lower-medium | Some consolidation, but time in bed may still be too loose or fragmented. |
| Below 75% | Low | A lot of the night is being spent awake or outside the main sleep interval. |
Do not overreact to one night. CBT-I works from patterns. A single bad night after stress, travel, alcohol, illness, or a late screen session is just data. A repeated pattern is what matters.
Pros and limits of using sleep efficiency
Sleep efficiency is useful because it turns a messy night into one consistent diary metric. It can help you notice whether time in bed is becoming more consolidated, whether a sleep window is too loose, and whether a change is holding across several nights.
But it also has limits:
- it is only as accurate as your diary estimate;
- it does not measure sleep stages or sleep apnea risk;
- it can look good on a very short sleep window even if you are too sleepy during the day;
- it should be interpreted with symptoms, safety, and clinician guidance when health risks are present.
Use the number as a trend signal, not as a grade for your body.
How sleep restriction therapy uses this number
Sleep restriction therapy is a CBT-I method that temporarily narrows the sleep window so your body rebuilds stronger sleep pressure. For broader context, see the science behind sleep restriction. It sounds counterintuitive, but the goal is not to sleep less forever. The goal is to spend less time lying awake in bed so sleep becomes more compact and predictable.
In a supervised CBT-I program, sleep efficiency helps decide when to adjust the sleep window:
- if efficiency is consistently high, the sleep window may gradually expand;
- if efficiency is consistently low, the plan may first focus on tighter timing and stimulus control;
- if sleepiness becomes unsafe, the plan needs to be adjusted.
This page is educational. It should not be used to set a strict sleep restriction schedule by yourself if you have a safety-sensitive job, untreated sleep apnea, seizures, bipolar disorder or mania history, pregnancy, severe daytime sleepiness, or any medical condition where sleep restriction could be risky. In those cases, talk with a qualified clinician.
Example calculation
Imagine this sleep diary entry:
| Diary field | Value |
|---|---|
| Time in bed | 8 h |
| Time to fall asleep | 20 min |
| Awake during the night | 30 min |
| In bed after final wake-up | 10 min |
Sleep efficiency:
(480 - 20 - 30 - 10) / 480 × 100 = 87%
Zomni app score:
(480 - 20 - 10) / 480 × 100 = 93%
Both are useful. The 87% score estimates the share of true sleep across the whole time in bed. The 93% Zomni app score reflects how the app evaluates the core sleep interval while tracking night wake-ups separately.
Why an app can help
The hard part is not the arithmetic. The hard part is doing it every morning, watching the trend, and changing the sleep window carefully instead of reacting emotionally to one bad night.
That is where a CBT-I app is useful. Zomni keeps a sleep diary, tracks your score over time, and helps connect the number to CBT-I habits such as stimulus control, sleep restriction, and a consistent wake time.
If you are comparing tools, start with our guide to choosing a CBT-I app or the side-by-side CBT-I app comparison.
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References
- Edinger JD, et al. Behavioral and psychological treatments for chronic insomnia disorder in adults: an American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine. 2021. DOI: 10.5664/jcsm.8986
- Spielman AJ, Saskin P, Thorpy MJ. Treatment of chronic insomnia by restriction of time in bed. Sleep. 1987. PMID: 3563246
Disclaimer: Zomni is a CBT-I-informed sleep improvement app, not a medical device and not a substitute for professional medical advice. If your sleep problems may be linked to a medical, psychiatric, medication, pregnancy, or safety issue, consult a qualified clinician.
