Some situations are a person have drive car or truck for a protracted time, when you stare in the computer monitor for hours, when you read or study especially something in which boring. http://enseignants.flammarion.com/Banners_Click.cfm?ID=86&URL=www.opticaljournal.com%2Fsjogrens-dry-eye-dry-mouth-and-knee-joint-pain-relief-by-theralife%2F