iOS version 5 has introduced a completely redesigned Notification system.
The new system is more flexible. At the same time it needs your input to run properly.
iOS 5 default setting has all application alerts/notifications disabled.
After upgrading to iOS5, make sure that you go to the Notification Center on your device.
On your Home Screen
Once you click on iStayHealthy you will be able to adjust the notifications, alerts, messages to your liking.