Im a 43 yr old woman and the back of my throat gets dry even during my sleep to a point i need to get water. whats wrong and cause ?

Dry throat during sleep can simply be an environmental problem. Try using a humidifier in your bedroom to increase the moisture level in the air. This will be especially helpful in the winter when heated inside air loses much of its moisture. You should also check your medications to make sure dry mouth is not one of the side effects. Oral lubricants such as Biotene can help with this.