Interupted sleep

This is an interesting article concerning interupted sleep patterns and Pca.  My own sleep pattern history is as follows: Four years as a Navy radio operator working rotating shifts...Nine years working for the power company working rotating shifts. And twenty five years as a professional firefighter with many sleep interupted nights. 

http://www.nbcnews.com/id/51795069/ns/health-cancer/#.UYja0sp8S_B