That's what sleep masks are for. Don't bring one? Tough.
Spoiled by flight deck seats, I suppose. Flew over Greenland at night one trip and Capt said I should stand and get a good look out the windshield. Spectacular sight on a clear night with pinpoints of light dotted here and there from FL410. Asked Capt. if he ever felt the urge to take her down for a closer look? Said yup.