About FoamNights
What This Site Covers
FoamNights is a small, focused site about sleep and mattresses. That means the mechanics of a night’s rest — sleep cycles, sleep debt, and sleep efficiency — and the physical side of sleeping well, mainly mattress sizing and firmness, plus one habit that quietly wrecks a lot of nights: caffeine timing. It does not try to be a general wellness site, a mattress review or shopping site, or a medical resource.
Concretely, the site is built around six calculators, a set of guide articles, and a museum. It is not built around brand comparisons, product rankings, or affiliate mattress reviews — you will not find “best mattress of 2026” lists here, because that is a different kind of site than this one.
What It Doesn’t Do
Every number on this site is an estimate produced by a plain formula, not a diagnosis and not personalized medical guidance. The sleep cycle, sleep debt, and sleep efficiency calculators are built on commonly cited sleep-science conventions (like the roughly 90-minute sleep cycle and the idea of accumulated sleep debt), not on a reading of your own physiology. If you have persistent insomnia, suspect a sleep disorder such as sleep apnea, or have an ongoing medical condition affecting your sleep, the right next step is a doctor or a qualified sleep specialist, not a calculator.
FoamNights is also not affiliated with any mattress manufacturer, retailer, sleep-tracking device maker, or sleep-science organization. Mattress types, materials, and terminology referenced here (memory foam, latex, innerspring, hybrid, and so on) are described generically, as industry-standard terms, not as endorsements of any brand.
Independent and Ad-Supported
This site is independently run and pays its bills through display advertising, which is why you’ll see ads alongside the tools and articles. There is no subscription, no account, and no data collection beyond what is needed to run the ads — using a calculator here doesn’t require signing up or handing over personal information.
The Tools
The Sleep Cycle Calculator counts back or forward in roughly 90-minute cycles to suggest bedtimes or wake times that land you at the end of a cycle instead of the middle of one. The Sleep Debt Calculator adds up the hours you actually slept over a week against a target and shows the debt or surplus, along with your average nightly sleep. The Sleep Efficiency Calculator takes your time in bed, time to fall asleep, and minutes spent awake during the night to work out what share of time in bed you actually spent asleep.
On the mattress side, the Mattress Size Calculator looks up standard US mattress dimensions in inches and centimetres, along with surface area, typical sleeper counts, and a comfortable minimum room size. The Mattress Firmness Finder suggests a firmness on a 1–10 scale from your sleep position and body weight, as a starting point for narrowing a mattress shortlist — not a substitute for lying on one in a showroom. And the Caffeine Cutoff Calculator uses caffeine’s half-life to estimate the latest time to have a coffee before it’s likely to interfere with falling asleep.
The Museum and Guides
Beyond the calculators, the Sleep & Mattress Museum is a set of galleries on mattress types from innerspring to memory foam and latex, the pillows, duvets, and bedding that dress a bed, the science of sleep cycles and circadian rhythm, and the sleep disorders that disrupt the night. Every entry, image, and fact there is drawn from Wikipedia and Wikimedia Commons, not written in-house. The blog and learn sections hold longer articles on the same topics, for anyone who wants more than a single number out of a calculator.
Questions, corrections, or a tool idea? Get in touch.