This is done either in sleep lab by a fixed machine or by a portable device which records everything at night in natural home environment and next day data is downloaded in computer. This over night data is analysed by putting markers on different places and finally interpretation is made by Dr S Z Jafrey who is #1 somnologist in Town. This takes few hours and finally report is created. Interestingly severity of hypoxia, AHI and Symptoms are all taken into consideration.
If CPAP is prescribed, then next night CPAP titration by auto CPAP / auto BiPAP is done to decide pressure and other settings.
Always take advance booking for PSG as machine remains busy.
Remember no homeopathy / aryuvedic / surgery by ENT can cure sleep apnoea. Only they can reduce or treat snoring. Remember all snoring are not apnoea and all apnoea need not to have snoring. If somebody does false claims, get your PSG pre and post procedure. If AHI is not controlled apnoea is not controlled.