Sleep study
I had to do 2 sleep studies, both at a sleep study facility. Basically, they hook you up to a bunch of electrodes and monitor your sleep to see if you have sleep apnea or any other sleep problems. You might do an at-home test where you attach some monitors to yourself. If you do it at a testing facility, they may or may not hook you up to a CPAP. My first one they did not, my second one they did.
Nothing to be alarmed about. Likely you won't get much sleep during the test. I went home and took a nap!
Jen