What causes sleep apnea?

1. this is general psychology assignment
2.Please be Apa format
3 do not use complex vocabulary, no profession words, use common grammar, simple sentence structure. By the way my ielts score is 6
4.i have upload some ppt include the topic ppt, assignment requirement, paper sample. have look and complete it by follow that.
5.the reference  you are going to use  provide me the digital address.
6. after u come out and idea of topic, inform me with the outline.