We try our best to ensure that Sandglass runs smoothly across all mobile devices. If you've experienced a bug, a crash or simply want to talk, you can write in to matter@offworld.info.

In the meantime, you can refer below for some answers.
How do I set a nap alarm?
1) Edit your alarm profiles. These are the buttons on the top (left and right). You will have two alarm profiles to toggle between, where you may set your alarm ringtone, alarm icon and vibration.

2) Select your nap duration. You can either choose a default alarm or a custom alarm. You may also long-hold to edit the snooze duration and note function.
What is the difference between default and custom alarms?
Default Alarms — You cannot edit the nap duration for default alarms as they are Sandglass' designated nap durations. These nap durations are chosen for a perfect nap experience. You can, however, edit the snooze duration and note function.

Custom Alarms — You can set the nap duration, snooze duration, alarm icon and note function. This is a feature only available if you have unlocked Sandglass.
How else can Sandglass be used?
Sandglass can also be used for — Games, cooking, work, school, events, competitions, sports and etc.
How do I edit alarm profiles/alarms?
To edit specific items in Sandglass, you have to long-hold on them. If you want to edit the alarm profiles, you long-hold on either of the alarm profile icons on the top. If you want to edit the alarms, you long-hold on either the default or custom alarm.
How much is it to unlock Sandglass?
To remove ads, it is USD $0.99. To unlock the full version of Sandglass, it is USD $2.99.
What do I get when I unlock Sandglass?
You will get full access to custom icons (for alarm profiles and alarm), custom alarms, infinite snooze limit, no ads and ability to set notes.
What is the note function?
The note function is like a gentle reminder when you wake up. For example, if you need to send an email after a nap, you can use the note function to remind yourself.
Sandglass does not ring until my Xiaomi phone is unlocked.
The MIUI on Xiaomi phones restrict third party applications' access. As such, it might be restricting Sandglass on your phone. Please look into the following steps: 

1) Go to Settings > Manage apps' battery usage > Select Sandglass > Select "No Restrictions." for Sandglass
2) Go to Settings > Permissions > Autostart > Select Sandglass > Turn the toggle to switch it on for Sandglass
3) Go to Settings > App Notifications > Select Sandglass > Turn the toggle for "Priority" on.
My custom ringtone (in my ringtone library) does not play.
Unfortunately, this is a problem we have been trying to resolve since the initial development stages. This is a Android-specific problem which we have no means of resolving at the moment. We suggest you use your custom music or phone's default ringtone as your alarm ringtone.
Does Sandglass run on tablet?
No, unfortunately it does not. We may look into it in the future. Please take note that Sandglass only works on mobile devices at the moment.
Is there an iPhone version of Sandglass?
There are plans in the future.
Would there be future updates?
Yes, definitely.