About the app
Which devices can I use it on?
Any iPhone running iOS 26.5 or later, and any iPad running iPadOS 26.5 or later. Mac is not supported.
How much can I use for free?
Everything in the current version is free. The three sleep sounds, the morning forest and bush-warbler wake-up, the records (how you woke this morning, the birds’ scoring, the shape of last night, the birds’ observatory, today’s word, exporting your records), the every-morning backup, the bedtime reminder, the morning background sound — all of it is available.
We are preparing a paid version in which many songbirds appear each day in a different order, but the current features will never become paid.
Will there be ads?
No. We have no intention of ever putting ads in this app. If we ever change this policy, we will let you know on this page and within the App, before the change.
About using it
Do I need to keep the screen on until morning?
No, you don’t. Once you set the alarm, you can turn off the screen, keep it locked, and sleep as usual. There is no need to keep the screen displayed.
How should I place my iPhone at night?
Keep it charging, at your bedside. It plays a very quiet sound all night long, which uses battery. Also, if the power runs out, the alarm will not sound.
If you’d rather not have a device that emits radio waves right next to your head, place it about one meter from your pillow. This alarm rises to a volume that is easily audible even from a distance. Even in Airplane Mode, this alarm and the iPhone alarm will sound (both run entirely inside your iPhone).
What volume should I set on the device?
We recommend 70–80%. This alarm begins at an almost inaudible level. If the device volume is too low, you won’t notice the start of the morning. If it’s too high, the finishing bush-warbler may startle you.
When the volume is low, a notice appears on the App’s main screen. When the volume is 0%, we tell you clearly at the moment you press “Good night.”
What if I fall asleep with the volume at zero?
The iPhone alarm (with vibration) wakes you instead.
Only when the (media) volume is exactly 0% does the following happen:
- If it’s 0% when you press “Good night” or start a nap, we tell you right then. You can also continue anyway
- If it’s still 0% when the start time arrives, the songbird voices are playing but inaudible. In that case, the iPhone alarm sounds exactly at that time. We do not shift the time
- The check happens 10 seconds before the start. If you raise the volume before then, this rule does not apply and you wake to the songbird voices as usual
- On any occasion the emergency alarm sounds, the next time you open the App we tell you on screen “when, with which settings, at what time it sounded”
If even 1% of sound is coming out, the App does nothing. This is so as not to disturb those who want to listen at a very low volume.
Note that the iPhone alarm’s volume is a separate control from the media volume (Settings → Sounds & Haptics). Even if media is at 0%, the alarm will sound.
Where do the sunrise and sunset times come from?
They come from no agency’s figures. The App calculates them inside your iPhone from the latitude and longitude of where you are. It does not communicate.
The calculation method follows the solar radiation calculation of the U.S. National Oceanic and Atmospheric Administration (NOAA), using the formulas in Jean Meeus’s Astronomical Algorithms. The horizon is set to the international standard of −0°50′ (34′ of atmospheric refraction + 16′ of the sun’s radius).
Compared against a standard astronomical library over a full year, the difference was an average of 1.8 seconds, maximum 5 seconds for cities in Japan. That is why we display to the second. An alarm that shows sunrise to the second is, we think, rather rare.
However, the following cannot be filled in by calculation:
- These are values for a flat horizon, at sea level, in a standard atmosphere. If there are mountains or buildings, the actual moment the sun becomes visible is later (and setting is earlier)
- The temperature and air pressure of the day can also change it by tens of seconds
It differs by 1–2 minutes from the weather forecast
In many cases, that is not an error. The forecast is the time for “the representative point of that city,” while the App is the time for exactly where you are standing. Both are correct for their own location.
Since the Earth rotates 360 degrees in 24 hours, 1 degree of longitude = exactly 4 minutes. Around Japan, moving about 23 km east or west shifts the time by exactly 1 minute. The north–south difference is much smaller — about 10 seconds per 30 km.
Should I set the wake-up time to when I want to get up?
A good guideline is 15 minutes before you want to get up. At the time you set, the forest sound begins very quietly, grows over about 15 minutes, and finishes with the bush-warbler.
Can I use it together with music or other apps’ sound?
Yes. Even if you were watching a video or listening to music before sleep, this alarm’s sound won’t stop. Conversely, you can use other apps while this alarm plays.
I woke up partway through and want to stop it
Press and hold the large circle on the morning screen to stop it. It’s set to press-and-hold so you don’t stop it by accident.
About waking
Can I really wake up?
In case the quiet sound doesn’t wake you, there is a backup. About 15 minutes after the set time, a clear bush-warbler voice sounds. And if the App itself was unable to produce any sound at all (the iPhone was force-quit, the media volume was 0%, and so on), the iPhone alarm (with vibration) sounds instead. If the bush-warbler was played successfully, this backup is automatically canceled — it is not an additional alarm for the case where you heard the bush-warbler but fell back asleep.
That said, if the iPhone’s power is off, nothing sounds. Even if the media volume is zero, the iPhone alarm will sound (the ringer/alarm volume is a separate control). Even so, on a morning you absolutely must not oversleep, please also use another alarm as a precaution.
What happens on a morning I forget to press “Good night”?
If it’s a day of the week you’ve set, the iPhone alarm sounds the bush-warbler (Settings → Every-morning backup). It wakes you even on mornings you forgot to press it.
Can I use it for naps too?
Yes. From “Nap” on the main screen, you can choose 5, 15, 30, or 45 minutes. At that time the forest sound begins and wakes you over about 15 minutes.
About records and analysis
What is “the birds’ scoring”?
It shows last night’s sleep as a score from 0 to 100. The baseline is not some general average — it is your own last 60 nights. 50 means “the usual you.” Closer to 100 means “above your usual,” closer to 0 means “below it.”
The score is calculated from eight numbers: how long you were in bed, the time you settled, the time you got up, how many times the iPhone moved during the night, how it sits against sunrise, and so on. How much each one weighs is learned, little by little, from the answer you give each morning to “How was waking this morning?” (one of seven). Scoring begins once 15 nights have gathered, and comes of age at 60.
This is a score the developer devised. It cannot be used for any medical judgement. Every part of the calculation can be read in the App’s “How the scoring works” screen.
What is “the birds’ observatory”?
It is your sleep report, inside the records. Choosing 7 days, 30 days, 90 days or everything, you can read graphs of how your sleep sits against sunrise, how your waking has shifted, how long you were in bed, a comparison between the sleep sounds, and your waking time by day of the week.
What the graphs draw is time in bed — not time asleep. The birds cannot know more than that.
Why are the names and sources of the analyses written out?
Where the report uses an established method (social jetlag, the Sleep Regularity Index, the phase angle of entrainment, and so on), we write its name and its source. Call a thing that has a name by its name. Do not give an invented name to something that has none. That is a rule of this App.
Tapping the gold band under a card’s heading opens “About this analysis,” where we write honestly what the original definition is and where this App’s calculation differs from it. For example, where the original research uses “the midpoint of sleep,” this App uses “the midpoint of time in bed.”
What is “the time you tried to sleep”?
Some people keep looking at the screen for a while after pressing “Good night.” That time was not time spent trying to sleep. So the App takes the moment when, after “Good night,” the iPhone locked and stayed locked for 15 minutes, and treats it as “the time you tried to sleep.”
This follows the same thinking as a sleep diary, which asks “what time did you get into bed?” and “what time did you try to sleep?” separately (Consensus Sleep Diary, Carney et al. 2012). It is not the time you fell asleep. An iPhone cannot know the time you fell asleep.
Note that all iOS tells an app is “unlocked” and “locked again” — there is no way to know that “the screen came on.” On an iPhone with no passcode, this time is not recorded.
The text is too small for me to read
The cards in the birds’ observatory can be tapped to read in large type. The text not only grows, the colours brighten as well. The ordinary screens stay as they are.
Can I take my records out?
In “See all records,” use “Export records” to put every record into a single file (CSV) and hand it to Mail, the Files app, and so on. It opens in Numbers or Excel.
About records and privacy
Are my wake records sent to anyone?
No. Records are stored only inside your iPhone and are never sent anywhere. For details, see the Privacy Policy.
What is my location used for?
Solely to calculate today’s sunrise and sunset times. The calculation is done inside your iPhone, and your location never leaves it. The App works even without permission.
If I change devices, can I carry over my records?
We’re sorry. At present, they cannot be carried over. You can, however, use “Export records” to put every record into a CSV file and keep it yourself. A mechanism to read them into a new iPhone is being prepared as a future task.
Other
Is there an Android version?
Not at present. We are focusing our energy on the iPhone version.
I’d like to use the sounds myself
All the songbird voices in the App were recorded by the developer (Akito Haga) himself. The copyright belongs to the recordist, and uses other than playback within the App (recording, copying, distribution, use in videos or in shops, and so on) are not permitted.
For inquiries, please contact otoiawase@kotorinokoe.com.