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Lull FAQ
Questions about the site as a whole. Questions about one tool are answered on that tool's own page, under its result.
Frequently asked questions
What is Lull?
A small set of sleep timing calculators at instacalc.co. Each tool takes a few inputs and gives clock times (a bedtime, an alarm, a nap length, a caffeine cut-off, a night-by-night travel plan) worked out from published guidance, with the sources shown. The full list is on the tools page.
Where do the numbers come from?
From one data file. The calculators use 86 of its values, each with a tier: 67 are read straight off a source page (CDC, NIH institutes, NIOSH, the CDC Yellow Book, the NHS, Canadian and Australian health bodies, the FDA, USDA and a few studies), 1 is reported by a source from another body, and 18 are our own rules of thumb. With the figures our sleep timing guides add, the file holds 129 values. All of them are listed on the methodology and sources page.
What is a studio rule?
A figure we chose because no source gives one, such as the 15 minutes the calculators allow for falling asleep or the bands on the social jet lag result. Each is labelled where it is used, with the reason on its methodology row. Some, like the minutes to fall asleep on the nap planner or the caffeine figure at bedtime, can be changed in the tool.
How often are the sources checked?
Every quarter, with a script that opens each source page and flags any that changed, plus a full read whenever a value is added. Each methodology row shows the date we last read its source, and every change to the site is dated in the changelog.
I think a number is wrong. How do I tell you?
Use the contact page and name the page and the value. We check it against the source, correct it if it is wrong and log the change in the changelog.
Is this medical advice?
No. The tools turn general guidance into clock times and cannot know your health. Every tool says, in a box below the calculator, what it cannot know and when to see a doctor. The full wording is in our disclaimer.
Is what I type stored or sent anywhere?
No. Every result is worked out in your browser. A share link holds only the inputs of one tool, and only if you copy it. The site uses Google Analytics and AdSense, described in the privacy policy.
Which tool answers my question?
The tools page lists each tool with the one question it answers. Night shifts and jet lag have separate planners: the night-shift sleep planner for daytime sleep after a shift, and the jet lag planner for crossing time zones.
Who runs Lull?
Quiet Hours Studio, from Serbia. The site is funded by advertising and has no other sponsor. More is on the about page.