Your Own Sound Experiment: How to Compare Nights Fairly

You try a new sound for a night, you feel rested the next morning, and it seems obvious the sound did it. Maybe it did. Maybe it was a quiet day, an earlier bedtime, or simply wanting it to work.

You can’t sort this out from one night. But a small, fair experiment gets you much closer. Here is how to set one up, and what to do with the answer.

Why one night tells you very little

Nights vary, even for the same person. A study of two weeks of sleep diaries from 592 adults found that night-to-night differences within the same person generally exceeded the differences between people, for several measures such as total sleep time and time to fall asleep (Dillon and colleagues, 2015).

A separate analysis of diaries from teenagers makes a related point: combining several nights reduces the effect of night-to-night variability (Short and colleagues, 2017). That study was about teenagers and about diary measures, so take it as an illustration of the idea, not a rule for adults.

So a good night after a new sound, or a poor one, is within the range of what happens anyway. That is why comparing needs several nights of each.

What you expect can color what you report

Expectation is the other trap. Two studies point in different directions, which is typical of this area.

In a 2014 experiment, students were given made-up feedback that they had slept well or poorly. The students told they had slept well did better on some mental tasks, while their own ratings of how they slept did not predict performance (Draganich and Erdal, as summarized by the British Psychological Society). A 2022 pilot study with 46 healthy sleepers gave good or poor made-up sleep scores and found no change in pre-sleep arousal or diary-recorded sleep continuity (Robson and colleagues). The pilot was small and measured different things.

Evidence: Emerging / Mixed. Small studies, different outcomes, and none of them used sound.

For sound itself, a 1994 loudspeaker study at a manufacturer’s lab asked 40 employees to rate four loudspeakers, once while seeing them and once without. When they could see the speakers, they rated the larger, more expensive ones higher. Without seeing them, the preferences changed (Toole and Olive, as described by Olive). It was small, old and from one lab, and it was about loudspeakers, not sleep sounds. Evidence: Emerging / Mixed.

The sources I read don’t include a study of this effect for sleep sounds. The careful reading is that what you know about a sound may shape what you say about it, so it is worth hiding that knowledge when you can.

A fair comparison, step by step

The ideas below come from n-of-1 trials, a design where one person tries two options several times in a random order. The 2024 guidance for them is written for health research, so borrow the structure, not the medical purpose.

1. Compare two things, not five. Sound A against sound B, or a sound against none. Keep volume low and the same on both (see our guide on safe listening volume).
2. Change only that. Keep bedtime, headphones or speaker, and your evening routine as steady as you reasonably can.
3. Repeat it. The guidance says the number of periods is a trade-off between precision and feasibility, and its review found six to be a typical number. More repeats tell you more, but they take longer.
4. Randomize the order. The guidance recommends blocked randomization, which means shuffling the order within each pair of nights, so you don’t get all of A and then all of B. Flip a coin for each pair: heads A first, tails B first. Doing it in blocks of two nights keeps the groups balanced, and it keeps a slow drift, such as a busy week, from landing on one option.
5. Blind yourself if you can. Have someone else pick the order and keep the key to themselves. If you can’t hide which one is playing, the guidance says a single-blind or open design is still acceptable, so keep going, and be honest with yourself about the limit. A night with no sound at all can’t really be hidden.
6. Write down your answer before anything else. Rate the morning with the same question and the same 1–5 scale, right after you wake, before you look at the key.
7. Watch for carryover. The guidance suggests a gap between options when one might linger into the next. Our own simple version: put a night of your usual routine between the two.

How many mornings you need

Enough that a lucky or unlucky night can’t decide it. A reasonable rule of thumb is at least 5 answered mornings for each option before you read anything into the numbers. A skipped morning is fine; it just doesn’t count.

We are designing OscillaMind, the sound-wellness app, around the same idea. Its quick morning check-in is planned to show a comparison only once there are at least 5 answered mornings in each group, always with the count (“on 5 of 7 mornings”), and to say “after”, never “because”. A planned Less Is Better run compares your routine with a lighter or silent version over 8 nights, 4 of each in a random order, and shows a result only with at least 3 counted nights in each. These features are in design and not yet available.

Reading the result honestly

Look at the counts, not at how strongly you remember one night. “Rested 4 or 5 on 4 of 5 mornings after A, and on 3 of 5 after B” is a fair thing to write down. It is not a conclusion about what a sound does to you.

“No clear difference” is a perfectly good result. It may mean the sounds are about equal for you, or that your test was too short or too noisy to show a difference. You can’t tell which, and that is fine.

A result also belongs to the weeks you tested, not to every night you have yet to live. If it matters to you, run it again some other month. And if you have concerns about your sleep or health, a doctor is the right person to ask, not a home experiment.

FAQ

How many nights should I compare? There is no magic number. The n-of-1 guidance says it is a trade-off, with six periods common in health research. A simple home plan is around 10 nights, 5 for each option, with the order shuffled.

Is a no-sound night a fair comparison? Yes, and it is often the most useful one. You will know which night it is, so write your morning answer before you think about it.

Can I run it blind by myself? Partly. Ask someone to pick the order, or prepare the options ahead and shuffle them. If you can still tell which is playing, note that in your records.

What if the results are the same? Then “no clear difference” is your answer. Pick the one you enjoy, or the quieter one, and move on.

Sources

1. Variability in self-reported normal sleep across the adult age span (Dillon et al., Journals of Gerontology B, 2015). https://experts.arizona.edu/en/publications/variability-in-self-reported-normal-sleep-across-the-adult-age-sp/
2. How Many Sleep Diary Entries Are Needed to Reliably Estimate Adolescent Sleep? (Short et al., Sleep, 2017). https://pmc.ncbi.nlm.nih.gov/articles/PMC5806561
3. Placebo sleep affects cognitive functioning (Draganich and Erdal, 2014), as summarized by the British Psychological Society Research Digest. https://bps.org.uk/research-digest/placebo-sleep-can-boost-your-mental-performance
4. Poor false sleep feedback does not affect pre-sleep cognitive arousal or subjective sleep continuity in healthy sleepers: a pilot study (Robson et al., Sleep and Biological Rhythms, 2022). https://pmc.ncbi.nlm.nih.gov/articles/PMC10899903/
5. Audio Musings by Sean Olive: The Dishonesty of Sighted Listening Tests (on Toole and Olive, 1994). http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html
6. The development of a set of key points to aid clinicians and researchers in designing and conducting n-of-1 trials (Chatters et al., Trials, 2024). https://pmc.ncbi.nlm.nih.gov/articles/PMC11241860/

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