Support

Email cmjonesapps90@gmail.com. It's one person, so give it a day or two, and include your iOS version and what you were doing when it went wrong.

Subscriptions

How much is it, and what's free?

The app is free. Logging, the dial, the sleep-safe countdown, last call for every drink, the caffeine curfew alert, the home and lock screen widgets, the brew calculator and exporting your data all stay free, with no account and no advertising.

SlumberBrew Pro is 99p a month or £6.99 a year, and adds:

There's also a completely free version in your browser at slumberbrew.com/try, if you want to check the maths before installing anything.

What happens if I cancel?

You keep every free feature, and nothing you've logged is deleted. The Sleep tab and the older history go back behind the paywall, and your data is still there if you subscribe again. You can export the lot at any time, free or paid.

I've paid but the app is asking me to subscribe again

Tap Restore Purchases on the paywall. That covers a new phone, a reinstall, or a restore from backup, as long as you're signed in with the same Apple Account you bought it on.

If it still doesn't unlock, email me with the Apple Account email you used and roughly when you subscribed.

How do I cancel?

In the App Store, not in the app. Open the App Store, tap your profile picture, tap Subscriptions, choose SlumberBrew, then Cancel.

You keep access until the end of the period you've already paid for.

Can I get a refund?

Refunds are handled by Apple, not by me, because Apple is the seller. Go to reportaproblem.apple.com, sign in, and find the purchase.

If something's broken, email me first. I'd rather fix it.

Why is there no free trial?

Because there's a free tier instead, and it's a real one rather than a demo. Use the app free for as long as you like and subscribe if the sleep half turns out to be worth 99p to you. That seemed better than seven days and a hope that you forget to cancel.

Questions people actually ask

Why does the app give me a range instead of a number?

Because a number would be a lie in most cases. Caffeine content in the same nominal drink varies wildly: a study measuring the same espresso order across twenty coffee shops found a roughly sixfold spread. Your home drip coffee could be half or double the figure in the catalog.

The drink catalog uses published averages because you have to start somewhere. The brew calculator gives a range because when you tell it how you actually brewed it, being precise about the uncertainty is more useful than being confidently wrong.

The number seems too high or too low for me

Change your half-life in Settings › Fine tune › Your metabolism.

Measured caffeine half-lives in healthy adults run from under 3 hours to nearly 10. That's not a rounding error, it's the difference between an espresso at 2pm being gone by bedtime and it still being half there. The app defaults to 5 hours because that's mid-range, but the default is a guess about you.

Rough guide: oral contraceptives roughly double half-life, smoking roughly halves it. If coffee in the early afternoon reliably wrecks your night, move the slider up. If you can drink espresso after dinner and sleep fine, move it down.

What does "sleep-safe" mean?

The time your estimated caffeine level drops below the target you set for bedtime. The default target is 25mg. The lowest single dose with published effects on sleep is around 100mg, so all three target options sit well below it.

It's a threshold you chose, not a medical safety line.

Why did my quick-add drink change to showing "227mg at bed"?

You're past the last call for that drink. Before that time, having one still leaves you under your bedtime target. After it, the app switches from telling you the latest time you could have it to telling you what it'll cost you. That's the warning, shown before you tap rather than after.

The widget isn't updating

iOS decides how often widgets refresh, and it budgets them. Tapping a drink on the widget updates it immediately. Between taps it can go stale for a while, which is normal.

If it's showing nothing at all rather than a stale number, remove the widget and add it again.

Do I need to connect Apple Health?

No. The dial, the countdown, last call, the brew calculator and the notifications all work without it.

Connecting it does two things: it reads your sleep so the app can show how caffeine at bedtime lines up with how you actually slept, and it can write the drinks you log back to Health as dietary caffeine so the rest of your health record stays complete. You can turn either off in iOS Settings › Privacy & Security › Health › SlumberBrew.

Where is my data?

On your phone. There's no account and no server. Settings › Data › Export your data gives you the whole lot as a JSON file, and Delete everything removes it.

If you delete the app, it's gone. We can't recover it, because we never had it.

I connected Health but there's no sleep data

The app looks at the last 90 days of sleep analysis. If nothing is recording sleep to Health (an Apple Watch, a sleep tracking app, or iPhone sleep schedule), there's nothing to read.

Apple deliberately doesn't tell an app whether a read was denied, so "connected, no sleep found" can mean either "you said no" or "there's nothing there". Check iOS Settings › Privacy & Security › Health › SlumberBrew to see what you granted.

Can it work out my half-life from my sleep ratings?

It could, and it deliberately doesn't. The data is far too confounded: a bad night could be caffeine, or a late meal, or a noisy street, or a stressful week. Silently rewriting the model your warnings are built on, based on that, would make the warnings worse while looking like a feature.

It shows you the correlation and lets you decide.

Is this medical advice?

No. SlumberBrew isn't a medical device and doesn't diagnose or treat anything. It's an estimate built on published averages, and the averages may not describe you. If you have a health condition, take medication, are pregnant, or are worried about caffeine or your sleep, talk to a doctor and go with what they say.

Where do the numbers come from?

Settings › The science lists every claim the app makes, what it does with it, and a link to the paper. The four that the model rests on:

If a claim can't be sourced, it isn't in the app.