I seem to get a cough while sleeping at night that wakes me up. it is a tickle in my throat? what is going on?

Post nasal drip/gerd: 2 reasons to develop a cough with lying down is reflux or post nasal drip.

GE reflux? Sinus?: Could be allergy to something in room (pet perhaps?) could be post nasal drip, dry throst from mouth breathing (stuffy nose), could be backflow of stomach contents (gastroesophageal reflux), other causes. Don't eat for 2-3 h b4 bed, elevate head of bed 4-6 inches, minimize coffee, chocolate, peppermint, fatty foods, tobacco. No relief? See md may need eval, antireflux meds and/or ent.

Possibilities....: Possibilities include post-nasal drip and gerd, both of which can cause bronchospasm that worsens when you lie down. The treatment for these is different so you need an evaluation by your doctor to determine if you have either of these.