Has anyone taken it? What are the amenities like? is it possible to sleep? Thanks

Welcome to SlowTrav!

I've only taken the overnight train between Zurich and Venice, but in looking at the tickets available on the sleeper train between Madrid and Lisbon, it looks as if the amenities are the same. You have a choice between a private sleeping compartment with berths or a shared compartment with berths, reclining seats or no reclining seats. A visit to the Rail Europe HERE website will provide you with your travel options and costs.

A friend and I shared a 'couchette' (shared compartment with berths) with two others, and while it was cozy it was fine for one night. It wasn't completely restful for me (the linking/ unlinking of train cars at the stops was noisy) but I know others who sleep like babies.

Colleen,
Thanks for the information. Whatever the comfort level, an overnight train surely qualifies as slow travel.

I just realized I should have told you that RailEurope costs are hugely inflated over what you'd pay if you waited to buy your ticket in Madrid. (At least 30% - on some tickets the uplift is 50%+). Keeping that in mind, you'll still get some idea of your expected cost.

That is really good to know. Thanks.