It is uncommon to miss important sleep apnoea, if the sleep study includes sleep while lying on the back and dreaming. [1 in 300 cases].
Snoring can be treated by avoiding sleeping on your back, weight loss or use of a mandibular advancement splint. We often suggest that people sow 2 pockets in the pajama shirt over their lower back- each slightly off one side with Velcro to hold them closed. Place a plastic practice golf ball in each pocket. Sometimes loss of 5 kg will help snoring, often, you need to lose more than 7 kg and keep it off to stop snoring a lot.
A mandibular advancement splint will pull the tongue forward when in place and help to free up the narrow airway. This will pull the tounge foreward with it. The lower jaw can move back and forth almost 12 mm. Many styles are available. Your own dentist or a dental specialist can provide one. Cost is often $1200 some start around $500: extra cover with health funds will often pay a rebate of $120.