Many visitors would be better off to put their watches in the drawer and leave it there while they are in the north country. Trying to stay on the same time schedule that a person uses in the Lower 48, doesn't always work too well. You have to stay flexible to enjoy the north, IMHO. As Doug (Veebyes) says, go till you are ready to sleep and then crash till you wake up and go again. I wonder if age might have something to do with this, as folks that have gone to bed at 9 PM for the last 70 years, may have problems changing. Don't know.
When you live in Alaska, you come to realize that there are things you have to get done in the summer before the cold of winter descends again, fire wood to cut and split, fish to catch, cut and dry for the dogs (my team consumed about 6,000 salmon a year plus white fish that I had caught late in the season and frozen outside), groceries to order for the winter, wild game harvested and prepared for the coming winter, etc. So sleeping a regular lower 48 schedule doesn't work for most residents of the north. You can sleep next winter, is the thought, but you find yourself just as busy. LOL
I spent the last 5 years of my working career, as a deputy coroner in Colorado and I don't ever remember listing "lack of sleep" as the cause of death for anyone. I think the dark curtains are part of the "adventure" of going to Alaska, just like some folks get all uptight about vehicle prep, plastic on the headlights, building wire cages around the front of the vehicle (haven't seen one of those contraptions in recent trips, and the list goes on and on. At times it seems that some get as much enjoyment from the planning and the worry as they do in making the trip. Actually it is all fun, just stay flexible and relaxed and all should go well.
I am now wondering if some people go to sleep with their eyes open, waiting for the sleep fairy to come close them and others close their eyes themselves while waiting to go to sleep. All of my life I have been one that needs little sleep at night, six hours being my average I would say. An that doesn't have to be in one stretch at a time, with two, three hour periods working just fine for me.
So in summer time Alaska, I may go to bed at 10 PM and sleep till 1 AM, get up and go fishing for a few hours, then come back and sleep for a few more hours. I remember several times waking up at 1 AM and deciding to fly into Fairbanks, which was a 3 hour flight, arriving there about 4 or 5 AM, (I usually would leave an old car at the airport for the summer) head down to one of the breakfast place like Sam's Sourdough, then downtown to shop for whatever I needed, and by last afternoon, be ready to fire up the airplane and head three hours west of Fairbanks, to where we were living. The air in Interior Alaska, in the middle of the night, is normally just silky smooth, due to the lack of heat thermals, making the ride in and out, just about like sitting in your recliner at home. Of course I was looking into the sun on both legs of the journey, for the most part.
So for anyone that feels they have to have it dark or wear eye coverings, consider if you really need to sleep or are you doing it out of habit. Make the most of your trip to the north country, don't spend it sleeping or watching TV, you can do that next winter. LOL If you aren't sleepy at 10 PM, then grab your camera and go for a hike, the light can make for great photography, easier to find wildlife, etc. Go out and set around the campfire, imaging what it would feel like if a bear was sneaking up behind you, go out and listen to the night sounds of the birds, the wind, nature.
Warned you that I buy pixels wholesale.