What can cause tightening/squeezing in the chest & nausea at night?

Acid, asthma, heart!: Most likely source of chest tightness occurring at rest at night with or without nausea is gastroesophageal problem (heartburn, acid reflux, ulcer). Another source is lung-related (asthma, COPD). The deadliest source is heart-related (heart attack, heart disease, irregular heartbeat, blood clot in heart/lung). GO TO ER NOW to rule out a heart problem!!! If ER clears you, then go to PCP for eval.

Stomach or heart: Symptoms may be from the heart and should be evaluated immediately. Because of you age, unless you have other med issues, I would guess you are experience "GERD"- gastroesophageal reflux disease- which would occur when you are laying flat at night. Try an antacid (i.e.: omeprazole- available OTC) before you go to bed.