I wanted to discuss the relationship between air quality and lung function, and the relationship between air quality and sleep disorders, in one sentence. Is there any efficient way to combine the phrases? If I use "Relationship between air pollution and lung function and sleep disorders" is it understandable?
It was understandable for me. You may want to write it using a comma like this:
Relationship between air pollution, lung function and sleep disorder
- I think sleep disordered (as you mentioned in your question) is refering to a person who is suffering sleep disorder. If you want to use the name of this symptom, sleep disorder is correct.
Source: Merriam-Webster dictionary's entry on the words: between & disordered