This is a type of study that usually deals with determining sleep disorders. This type of test will be able to check out your brain waves to see if there are any irregularities that you should know about. Aside from the brain waves, this also checks out the amount of oxygen that can be found in your blood. It also checks your current heart rate and how normal your breathing is when you are asleep.
There are also some people whose leg movements may determine if there is a sleeping problem available. If you suspect that you have some issues, this study may be useful to you.