Traveling overnight can be an inexpensive way to get somewhere and is sometimes your only option for transportation.
And if it's a long trip, you might as well get some rest without having to pay another night's accommodation.
We traveled by private coach bus at my job in Europe and would leave on Thursday evenings. While some trips were only a few hours each way, others took all night. Florence to Budapest, Hungary; Florence to Split, Croatia; and Florence to Prague, Czech Republic were a few trips in particular where we would be traveling for 10-12 hours straight. By the time we arrived, it would be morning of the next day and we'd be off to start the trip's activities.
Being comfortable and having at least a semi-decent night's sleep on the overnight bus or train is essential. If you're not somewhat well rested, then the next day will just drag on as you attempt to explore through weary eyes and a cranky attitude.
Whether you're on a bus, train, or even a long haul flight, there are essentials you must bring with to ensure the most comfortable night possible:
Earbuds/Headphones
For entertanment, to keep out miscellaneous noise, or to help you wind down.
Scarf
Whether you're a guy or a girl, you'll benefit from having a scarf with you. As a fashion statement or as simply something to keep warm, a scarf is a must-have. I've used scarves for many reasons, but mostly to keep warm or as a pillow.
Makeshift "bed" items: neck pillow and travel sized blanket
To get some real sleep, you'll need to be as comfortable as possible without sacrificing room in your luggage. A neck pillow will be worth it after traveling for hours on end, and if you forget a scarf (or don't have a scarf that's good enough for the occasion) then a travel blanket (compact, warm but thin, and enough to cover at least your legs) will do.
Melatonin
This is an over-the-counter sleep aid that makes you tired. It's nice to have on hand when you have a long journey and just want to sleep through it all.
Sunglasses and/or eye shades
Because there are windows, which means sun in your eyes during the day or headlights from oncoming traffic at night.
Water bottle and snacks
Overnight journeys tend to be long, and you don't want to go without water or food if you're not stopping along the way.
Portable phone charger
If you're like most people, you probably charge your phone while you're asleep. Having a portable battery pack is handy for overnight rides, since oftentimes you'll be without a power source to charge your phone for a night. This way you'll have your phone ready to use the next day when you're out exploring.
Pocket Coffee
Some countries in Europe sell Pocket Coffee, which is a packet that includes bite-sized chocolates that are filled with a liquid shot of espresso. These are so nice to have on hand for the next morning when you need an extra jolt! Otherwise, definitely grab a coffee or fresh glass of water when you arrive to get energized for the day!