SchlummerSchlummer guide
Sleep Tracker for iPhone Without an Apple Watch
A phone on the nightstand cannot feel your pulse. It can hear the room. That single fact explains everything a watch free sleep tracker is good at, and everything it will never tell you.
What the phone actually measures
Schlummer opens the microphone when you start the night and never stops until you end it. It does not keep the audio. It keeps a number: the loudness of the room, averaged and written down once every five seconds. Over eight hours that is around 5,700 readings, and they are the entire raw material of your sleep report.
Each reading is sorted into one of four bands by how loud it is. A near silent stretch reads as deep. A faint rustle reads as light. More movement reads as REM. A noisy stretch, a conversation, a trip to the bathroom, reads as awake. Chain them together and you get the stepped curve you see in the morning, plus a single score between 1 and 100 that rewards the quiet parts of the night and subtracts for the loud ones.
This is worth being blunt about. The bands are named after sleep stages because those are the words everybody uses, but they are derived from sound alone. They are a picture of how restless your bed was, not a reading of your brain. Schlummer says the same thing inside the app, on the morning screen.
Phone, watch, sleep lab
Three very different instruments get called sleep tracking, and they answer three different questions.
| iPhone microphone | Wrist wearable | Sleep lab | |
|---|---|---|---|
| Signal | Room loudness | Motion and heart rate | Brain waves, eye movement, muscle tone, breathing, oxygen |
| Good at | When the bed was restless, and how loud you were | When you fell asleep and woke, and how your heart behaved | Actual sleep stages and breathing events |
| Blind to | Anything silent and still, and it cannot tell you from your partner | Sound, so no snoring evidence without a microphone | Nothing much, which is why it is a clinic and not an app |
| You have to | Charge the phone and leave it on the nightstand | Wear something to bed and charge it during the day | Book an appointment and sleep somewhere else |
| Cost | An app | A device plus usually an app | A referral |
None of these replaces another. A microphone is the only one of the three that hands you a recording of your own snoring, and a wearable is the only one of the three that keeps working when you sleep somewhere without a nightstand.
Getting a usable night out of a phone
- Plug it in. The microphone runs all night and the screen sleeps but the app does not. Charging overnight is the difference between a report and a dead phone at 5:00.
- Nightstand, not under the pillow. A pillow muffles exactly the sounds the app is listening for, and it traps heat around a charging phone.
- Ringer on. The alarm plays through the audio session, and a local notification is scheduled as a backup. Both want a phone that is allowed to make noise.
- Leave the app in front. Start the night and put the phone down. Force quitting the app ends the tracking.
- Give it a few nights. One night is a data point. The curve becomes interesting when you can compare Tuesday with the Saturday you went to bed at 2:00.
Schlummer tracks, records and wakes you using nothing but the iPhone you already charge at night.
Free, iPhone only, iOS 17 or later. No account.
What you get in the morning
The morning screen holds four things: the score, how long the night lasted, a snoring figure derived from how many seconds of loud audio were captured against the length of the night, and the clips themselves. Below that sits the stepped curve with its four bands. Everything is computed on the phone, and everything stays there.
Where to go next
- How the light sleep alarm uses the same signal to pick a moment inside your wake window.
- What the snore recorder writes to disk, and why it is a handful of clips rather than an eight hour file.
- Pillow compared, if you are weighing whether to buy a watch after all.
- Sleep Cycle compared, the other well known phone based tracker.
Schlummer is a wellness app, not a medical device. It does not diagnose sleep apnea, insomnia or any other condition, and it is not a substitute for advice from a doctor.