Hi, sleep apnoea definitely makes you feel tired. This is because the sufferer does not get good sleep due to constant startling awake when they do not breathe. Daytime tiredness and sleepiness is a hallmark of sleep apnoea.
You have done the right thing in setting up an appointment for sleep studies.
This is also pretty disconcerting for the sleep apnoeas bed partner.
Thinking of you both,Tammy.

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!