Because the heavy snorer (and google sufferer) does have small awakenings (up to 300-400 times a night) to get a breath, he is constantly tired during day time.
You always be at risk for OSA if tend to be overweight, over 65 associated with age, or smoker. Men are at high risk for OSA than girls. Also, if you have family members history of OSA, the more likely to develop the condition.