There is no shortage of sleep apps. Sleepa is different in one way: it was built around a physician who specializes in sleep. Why would a doctor want to make an app that people use at home, far from the clinic? This article tells the story behind Sleepa.
About this article
This article is written by Masa, an engineer and co-founder of Medisense Inc., the company that develops Sleepa. Medisense was founded in Japan in August 2024 by three people: Dr. Kimura, a physician; Asada, a lawyer; and me. After more than a year of development, we released Sleepa on the App Store in November 2025.
The doctor behind Sleepa
Dr. Norihisa Kimura, who heads Medisense, runs his own clinic, Kimura Medical Clinic, in Kawanishi, Hyogo, Japan. He is a neurologist whose practice covers sleep problems as well as conditions such as Parkinson’s disease and dementia. The ideas behind Sleepa’s features, and the explanations about sleep inside the app, are based on his clinical experience.
- Director, Kimura Medical Clinic; Head of Kishokai Medical Corporation
- Clinical Associate Professor, Tohoku University School of Medicine
- Board-certified neurologist; Certified Physician, Japanese Society of Sleep Research
- B.S. in Physics, Faculty of Science, The University of Tokyo
* University titles are listed as part of Dr. Kimura’s personal background. Sleepa is not a product of university research and is not endorsed by any university.
Insomnia care starts with listening
It may come as a surprise, but when someone sees a doctor about insomnia, the diagnosis rests mostly on what the patient says. When did you go to bed? When did you wake up? How many times did you wake during the night? On which nights do you feel you didn’t sleep? From the answers, the doctor builds a picture of how the patient sleeps.
There is a test that measures sleep objectively: polysomnography (PSG), which records brain waves, breathing, blood oxygen and more over a full night. It is precise, but it usually means spending a night at a sleep lab, so it is not something most people can do casually. And it only captures the night of the test.
So in many cases, the doctor has little more to go on than the patient’s own sense that they aren’t sleeping.
Not sleeping vs. feeling like you’re not sleeping
The trouble is that how we feel we slept and how we actually slept don’t always match. Even healthy sleep includes many brief awakenings during the night. Most are so short that we never remember them. But if the time between those awakenings also feels like being awake, the night can feel completely sleepless.
Feeling that you didn’t sleep when you actually did, at least to some extent, is called sleep state misperception (sometimes “paradoxical insomnia”). Dr. Kimura says it is not unusual among the people who come to him about insomnia. I wrote more about it in What is sleep state misperception?
Check first, before thinking about medication
When sleeplessness is wearing you down, sleep medication is an important option, and for people who need it, it is essential treatment. At the same time, some sleep medications carry risks such as dependence, and health authorities encourage using them appropriately and not for longer than necessary.
For most physical conditions, doctors confirm what is going on before starting treatment. We wanted the same for sleep: start by finding out what your sleep actually looks like. That was where Sleepa began.
If you already take sleep medication, please don’t reduce or stop it on your own. Always talk to the doctor who prescribed it.
Apple Watch can record every night, at home
That is where Apple Watch came in. Using a motion sensor that picks up movements of the wrist, Apple Watch estimates which of four states you are in through the night: Awake, REM, Core and Deep.
It is not as precise as a lab test. But you can wear it while you sleep at home as usual, every night, for weeks on end. That reveals things a single night in a lab can’t: how your sleep changes from day to day, and what your own pattern looks like.
If you could see your feeling of “I didn’t sleep” side by side with what your Apple Watch recorded, that might help you understand your sleep. Sleepa took shape through many conversations between a doctor and an engineer about that idea. For tips on reading the data itself, see How to read your Apple Watch sleep data.
What matters to us in Sleepa
Several parts of Sleepa borrow from how sleep problems are handled in the clinic.
- Record how you felt, too: we turned the sleep diary used in clinics into a feature you can compare with your Apple Watch data on the same graph (about the sleep journal).
- Rules decide, AI only explains: findings are determined by fixed rules, and the AI only turns the results into readable text. That keeps the criteria in a form a doctor can check (about the AI sleep analysis).
- No diagnosis: Sleepa is not a medical device and does not diagnose any condition. We want it to be a prompt to talk to a medical professional when something looks off.
- Your data stays on your iPhone: sleep data is sensitive health information. Analysis and AI text generation run on your iPhone, and your sleep data is never sent to an external AI service.
Looking ahead
At Medisense, our goal is to make healthcare a source of happiness through the power of information and communication technology, for the people who receive care and the people who provide it. We want the data from everyday life to help people understand their own bodies, and one day to help connect patients and doctors. Sleepa is our first step.
In this column, we will keep sharing what is worth knowing about sleep and how to get the most out of Sleepa. If you have feedback or questions, please get in touch through our contact page.
Sleepa — The Science of Sleep
Look back on the sleep your Apple Watch measures, together with AI sleep analysis and your sleep journal. Learn more about Sleepa.
* Requires an Apple Watch (Series 6 or later) and an iPhone with iOS 26 or later.
Please note: Sleepa is not a medical device. Its analysis is for reference only and is not a medical diagnosis. If you have symptoms that concern you or are worried about your sleep, please consult a medical professional.