Over Easter, I took a quick impromptu holiday break from London to Edinburgh. Being a last minute sort of deal, most flights and train tickets were pretty expensive, but I managed to get a few seats on the sleeper train departing Euston around midnight and arriving in Scotland the following morning at around 7am. Sounds great right?
Now that I've experienced the trip there (and back), a few things I wish I'd known and things to note:
Don't take the seats shared section if you are a light sleeper
The lights in the seated section don't get turned off, or dimmed. Eyeshades are provided, but if you aren't used to sleeping with these, you're going to have a rough time.
If you get to select your seat, I recommend in the center of the cabin - the doors are quite loud when they open and close, and they will do so pretty often as passengers leave the shared section to get to the toilets.
On my journey there, for some insane reason the carriage became extremely, extremely hot and muggy (I suspect that someone had requested the heating turned on and the staff forgot to turn it off), so wear your clothing in layers so you can adjust to the temperature. (The sleeper berths supposedly have air conditioning so you don't have to deal with this)
Bring your own food and drink
While on paper there's counter service available to seat passengers in the lounge car where you can buy refreshments, this was not open for the entirety of my journey both to and from Edinburgh. Bring your own supplies for midnight snacking / breakfast pick-me-up, don't expect to be able to buy anything on board.
You won't be able to upgrade to a cabin from seated (kinda)
You can call the help centre to try, who will tell you that you can inquire with the welcome staff and upgrade if there is availability.
Well, the "welcome staff" will probably arrive late. And when they do, they'll have a list of cabin passengers, but if you ask one of them about upgrading from seated to a cabin, they'll tell you to ask the other person. The other person will tell you to ask the initial person. The initial person will tell you it costs an extra £100 and you should stay in your seat and you might get a free cabin.
This is a lie, they will just ignore you and you will remain in your seat, stuck with the smell of smelly feet and judgmental ladies.
It's not all doom and gloom
Arriving on the sleeper train is cheaper (you save on a night's accommodation), and arriving at 7am in the morning means you can beat the majority of the tourists to Edinburgh Castle, Holyrood Palace, and so on. Plus, arriving at Waverley train station means that the instant you exit the train station you're seeing a lot of famous landmarks already (the Scott Monument, the castle in the distance, Calton Hill)
Apparently new trains will be running the line in 2018, so it might alleviate a lot of these issues, but until then, I'd probably recommend a cabin. Arriving in Edinburgh by train is really quite the experience though, so if you're the adventurous type, give it a go!