As subscription payments are handled by Apple's App Store (and not by Sleepiest directly); our support staff are are unable to cancel your subscription via email or support ticket.
In order to cancel your subscription you must therefore follow the cancellation steps within Sleepiest.
To cancel your subscription, please follow the steps below:
Navigate to the "Profile" tab.
Press the settings cog in the top-right corner of the screen.
Press "Account Options".
Select "Manage My Subscription".
Select "Cancel Subscription".
Select a cancellation reason.
A prompt will appear which will take you directly to the "Subscriptions" section of your iTunes account.
Select Sleepiest from the list of subscriptions.
Scroll down the the bottom of the screen, and select "Cancel Subscription".
Note: if you have not started a Sleepiest free trial or subscription then "Manage My Subscription" will not appear as an option. To confirm you have no active Sleepiest subscription you can check your current active app subscriptions by clicking here.