Sophia-Istanbul Express train

I have not; I sleep very poorly, if at all, on night trains, so I'd either fly or do the trip (by bus if necessary) in daytime chunks.

There's information on the Seat61 website, which calls the sleeping cars "comfortable", so I am perhaps unduly pessimistic. The website has some photos as well.

Thank you all. Just wondering if the train is comfortable. We are trying to decide on where to use our frequent flyer miles and one idea was into Sophia and out of Istanbul, but we definitely want to see more places in Bulgaria. Guess we could take a bus from Plovdiv into Turkey. We will most likely rent a car in Bulgaria, but do not want to take one across the border. Hopefully, Bulgaria has one way car rentals.

This train typically requires an in-person border check between 1:30 - 2:30 a.m. It has not been one of those routes where the conductors holds your passport to take care of it for you.