Hi.  I was diagnosed with sleep apnea almost 2 years ago.  The main cause of sleep apnea is the relaxation of the breathing passage during sleep.  This causes the breathing passage to close waking up the sleeper a little till it opens.  It typically prevents REM sleep and can cause severe tiredness and has been linked to heart disease.  http://www.sleepapnea.org/  has more information if you would like to read up.  

There are a few different types of treatment.  1)  CPAP - constant positive airway pressure device to be worn during sleep 2) dental appliance and 3) surgery.  It does not sound like your son's is very serious.  Did he have a sleep study?  As a reference my first sleep study found I had 85 apnea's an hour and my oxygen intake dropped.  As a young boy I had my adenoids and tonsils removed which can help in apena cases.  It was NOT a big deal.  I ate ice cream in the hospital and only had really a scratchy throught that I can remember.  It was probably a little more involved but young kids bounce back very quickly.

I had a UPPP surgery last year and I am needing to have my jaw repositioned this year to hopefully fully correct my apnea problem.  I wish you luck.  I am sure everything will be fine.