The "GO" can be used while sitting, standing, walking, or driving. 

Don't use it while sleeping as it's designed to be worn throughout the day and can't measure your posture while sleeping.
Get a good night's sleep of 7-8 hours, and make sure that you sleep comfortably. 

Be sure to charge your GO when you're not using it in order for it to be ready for tomorrow. 

Good night! :)