I've never had trouble hearing anything important through earplugs, and my phone alarm is not very loud. I sleep in earplugs whenever I travel, and also on nights when DH is snoring or thrashing. The main issue I have is increasing sensitivity of my ear canals. I can barely wear the Hearos Ultimate Softness any more. I got a pair of custom earplugs made, which are good as long as I sleep on my back (which I do most of the time anyway).

I wonder whether they'll find that it's the same genetic pathways that are switched by any disruption of the circadian rhythm - since I've also read that lack of natural light contributes to obesity. One of the things that's most frustrating to me is learning how important natural light is (both by reading and by personal experience), and yet knowing that for most people in the developed world, being able to sleep in the dark and wake to the light, never mind getting sunlight during the day, are unattainable luxuries.