"The sleeper train business is booming this summer. Across Europe, the bunks on overnight trains—once viewed as a fading anachronism in an era of cheap EasyJet and Ryanair flights—are sold out, and even tickets for simple seats are hard to come by.
The resurgence is being driven by concerns about climate change and the emissions from those cheap jet flights. But environmental consciousness is also making Europeans rediscover the perks, efficiencies, and subtle luxuries of overnight rail travel."
https://slate.com/business/2023/08/sleeper-car-trains-trend-travel.html