A pulse oximeter can also be worn overnight to check for oxygen desaturation during the night from pauses in breathing.

Polysomnography (sleep test) is the gold standard, but O2 saturation is a good indicator as well.

An oximeter isn't a bad thing to own and can be had cheaply from Amazon. Sleep apnea can emerge with as little as 10% weight gain, acid reflux or allergies. If you really care about your sleep, heart and brain it doesn't hurt to check once in a while.