Sleep Reference Library: free data, tools and charts you can cite

Most of what is written about pillows online is a list of product recommendations. This page is the other thing: the underlying numbers, formulas and datasets that those recommendations ought to be based on — published openly so anyone can check them, argue with them, or reuse them.

Everything on this page is free to reproduce, redraw or embed under CC BY 4.0, with a link back to the source page. Journalists, clinicians, physiotherapists, ergonomics teachers and other site owners are all explicitly welcome to use it. You do not need to ask.

Reports

Pillow Transparency Report 2026: What 32 Pillow Brands Leave Out

Report · 32 pillows · 3 charts · published 20 September 2026

What pillow brands tell buyers, and what they leave out: loft figures, how they are measured, firmness ratings and return windows, read from 32 official product pages.

Headline finding: 20 of 32 pillows give buyers 30 days or less to return them, exclude pillows from returns, or publish no window at all — and only 2 of 13 adjustable-fill pillows state any height range.

Datasets

Pillow Loft & Specification Database (32 pillows)

Dataset · 32 products · 12 fields · captured 15 August 2026

Published loft, fill type, firmness, adjustability, cooling claim, trial window, warranty and price for 32 pillows sold in the United States, transcribed from manufacturer pages with a source link on every row. Gaps are recorded as “not published” rather than filled with estimates.

Headline finding: exactly half the pillows — 16 of 32 — publish a loft measurement at all. Among adjustable-fill pillows, where height is the entire selling point, just 2 of 13 do.

Sleep Position and Pain Map (position × mattress firmness)

Dataset · 4 sleeping positions × 3 mattress firmnesses × 3 frame widths · captured 18 August 2026

Every combination of sleeping position and mattress firmness mapped to the supported pillow loft it requires, to what happens mechanically if the pillow does not change, and to what the published literature actually shows about pain in that position. Loft figures are arithmetic from the calculator formula; every pain claim carries a link to the study. Where no study exists the cell reads “not published”.

Headline finding: mattress firmness alone moves a side sleeper’s target loft by 1.25″ — two and a half times the ±0.5″ tolerance — and in 7 of the 9 frame-and-mattress combinations no single pillow height sits within tolerance of both side and back sleeping.

Night-Time Symptom Reference (50 symptoms)

Dataset · 50 night-time symptoms · published 29 August 2026

Fifty night-time symptoms mapped to the sleeping position associated with them, the likely mechanical cause, what published sources say to change, what each symptom is commonly confused with, and the sign that means the problem belongs with a clinician rather than with bedding. Every claim carries its source, and where the literature is silent the row says so.

Headline finding: for 13 of the 50 symptoms no published source describes any bedding change at all — the honest answer for those is that a pillow is not the lever.

Tinnitus and Sleep Evidence Reference

Reference · 5 sourced tables · published 11 September 2026

How often tinnitus disrupts sleep across the published studies, why it is louder in silence, what controlled evidence exists for each thing people try (sound enrichment, insomnia treatment, melatonin, ginkgo, zinc, supplement blends), the named ingredients of the reference hearing supplement with the evidence found for each, and the red flags that mean a clinician rather than a bedtime fix.

Headline finding: most studies put sleep disturbance in tinnitus patients above 40%, and of the common fixes only sound enrichment and treating the insomnia itself are supported — ginkgo (12 trials) and zinc (3 trials) are not, and no hearing-supplement blend has a published trial.

Tools

Pillow Height Calculator

Interactive tool + static reference table · 27 combinations

Computes the supported pillow loft your body needs from sleeping position, frame width and mattress firmness. Supported loft is the gap between ear and mattress once the shoulder has sunk in — which is why a soft mattress needs a lower pillow, not a higher one.

The full 27-combination result table and the underlying formula are published as static text on the page, so the answers are readable without running the tool. The calculator is free to embed on clinic and practitioner sites with attribution.

The formula: supported loft = ear-to-mattress gap − shoulder sink. Base gaps are 5.0″ narrow / 5.75″ average / 6.5″ broad for side sleeping and 3.5″ / 4.0″ / 4.5″ for back sleeping; shoulder sink is 1.5″ on a soft mattress, 0.75″ medium and 0.25″ firm, halved for back sleeping.

Tool · added September 2026

Seven-night sleep diary and sleep efficiency calculator

Records lights out, time to fall asleep, night-time wakefulness and final waking, then derives time in bed, total sleep time and sleep efficiency for each night and for the week. Flags nights over the 30-minute sleep-onset and wake-after-sleep-onset marks and nights below 85% efficiency, and prints a one-page record for a clinical appointment. Also records morning pain and sleeping position, which is what connects it to the rest of this library. Runs entirely in the browser; nothing is transmitted or stored server-side.

Free to use, print, adapt and embed under CC BY 4.0 · Open the tool · Printable PDF · Embeddable version

For machines

Everything above is also published in formats an automated system can read directly, so there is no need to scrape the pages. Same CC BY 4.0 terms, no API key, no rate limit, no registration.

Data files and API

Open endpoints · CORS enabled

Building something with this? The loft endpoint is the useful one: give it a position, a build and a mattress firmness and it returns a height range in inches plus the pillows that actually fit it. It is free to call from a clinic site, an app or an AI assistant. Tell us at hello@sleepalign.org if you need a field we do not expose yet.

Using any of this?

No permission needed and no need to ask first. One tap copies what you need.

CC BY 4.0 — reuse, redraw or embed with a link back.

How this material is produced

  • Manufacturer sources first. Specifications come from the manufacturer’s own published pages, with the URL recorded. Retailer listings and review-site figures are not used to fill gaps.
  • No first-hand product testing. This site does not buy, test, weigh or sleep on the products it writes about, and never claims to. Where buyer experience is discussed it is described as public buyer reports, not as our own testing.
  • Missing data stays missing. If a brand publishes no figure, the cell reads “not published”. Nothing is estimated, inferred or averaged into place.
  • Dated and revisable. Every dataset carries a capture date. Corrections are welcome and get made.
  • Geometry, not medicine. The loft ranges here are arithmetic about body dimensions. They are not clinical advice, and persistent pain is a matter for a clinician.
Using this material? Take it — no permission needed, a link back is all that is asked. If you would like a chart in a different format, a wider dataset, the raw figures behind a table, or the calculator as an embed for your own site, write to hello@sleepalign.org and it will be sent over.

Spotted an error, or know a manufacturer figure recorded here as missing? Send the link and the row gets corrected.

SleepAlign is an independent, self-funded pillow research site run by Bogdan. It is not a clinical practice and carries no medical credentials. Some product links elsewhere on the site are affiliate links; nothing on this page is.