I traveled 600 miles by train from London to Berlin instead of flying, and I don't plan to do it again. Here's why.

• I traveled by train from London to Berlin and back, taking the Eurostar as well as a sleeper train.
• Door-to-door the journey there took nearly 24 hours, including a few hours' layover in Brussels.

Last month I traveled by train from London to Berlin and back.

It's not an experience I plan to repeat.

A new sleeper service launched in Europe in May, shipping passengers between Brussels and Berlin. I decided to test the European Sleeper out, and paired it with a Eurostar from London to get me to Belgium in the first place.

Some travelers are choosing to make their trips more sustainable by avoiding flights wherever possible and instead opting for long-distance trains, coaches, and car-sharing apps. France and Austria have even banned some short-haul flights.

I'm no stranger to public transport. I took the train to and from my high school in the UK for seven years, took the six-hour coach journey between Newcastle and Liverpool many times, and spent a year studying in Germany where I traveled on its network of trains, trams, and buses.

But a sleeper train was completely new to me. My longest train journey had been five or six hours.

I arrived at London's St. Pancras Station after a 30-minute rush-hour tube journey, breezed through the security checks, and boarded the 9:01 a.m. Eurostar train to Brussels. But due to a security incident at Lille, the two-hour journey ended up taking four-and-a-half hours. I spent the time reading, writing, and napping. By the time I arrived in Brussels, it was around 2:30 p.m. local time.

I'd never been to Brussels before and wanted to use this trip as an opportunity to explore the Belgian capital, so I had deliberately booked my two trains – each with a different provider – with a six-hour layover there. The Eurostar delay cut into a lot of this, but I'm glad I left myself with plenty of wriggle room in case of journey disruptions. I also enjoyed the opportunity to stretch my legs, even if I did spent most of my time in Brussels in the line for a must-visit cheese-sandwich shop.

I headed back to the station for the second leg of the journey, this time the 6:01 p.m. European Sleeper, headed for Berlin. Because of the Schengen Agreement, I didn't have to go through security checks and could just rock up to the platform and board the train.

I'd decided to book their lowest-price ticket, which was a seat in a six-person compartment rather than a bed. It cost me 119 euros (around $130).

For the first hour, I was alone. The interior of the compartment seemed a bit dated – I was surprised to find there was nowhere to charge my phone – but at least I had plenty of space, I thought.

I was wrong.

Two passengers got on at Antwerp, an hour into the journey. Then, three more got on at Amsterdam at around 9:30 p.m., and our compartment was full.

I'm glad I brought food with me – I couldn't see any information on board about where to buy food and overhead a member of staff telling a passenger that the card machine was broken.

I'd set 10:30 p.m. as my bedtime. I knew my train would get in before 7 a.m. and I had a busy day in Berlin coming up. I brushed my teeth in one of the small sink-only rooms on the train and used the restroom. Most of the bathrooms on the train were out of order, some of the passengers were saying.

I put in my ear plugs, got out my travel pillow, took a sleeping pill, and put on my eye mask. And slept.

Or at least, that's what should have happened. Instead, I had one of the worst night's sleep of my life.

It seemed to be impossible to get comfy on the train's rigid seats. The people in the compartment next door were talking loudly and we were crammed like sardines with very little leg room, meaning that we woke each other up whenever we left the compartment. Though there were only eight passenger stops between Brussels and Berlin, the train stopped many more times than this. I would drift off to sleep for 20 minutes, only to wake up and be unable to settle again.

I noticed that someone had disappeared from our compartment. I presumed he had maybe found an emptier compartment to rest in. Later, I discovered that he had actually resorted to sleeping in the corridor instead.

We pulled into Berlin at around 6:30 a.m., slightly ahead of schedule.

"How did you sleep?" I asked the woman next to me.

"So-so," she said.

In all, I estimate I got around three hours' sleep. Like a true Brit abroad, I arrived in the German capital desperate for a cup of tea. I'd left my apartment at 7:20 a.m. on Wednesday and arrived at my hostel at around 7 a.m. on Thursday – a nearly 24-hour journey if you account for the change in time zone. From the time I arrived at St. Pancras to my arrival time at Berlin's station, it took close to 23 hours.

Despite my lack of sleep, I powered on ahead with my busy day of exploring, but I definitely would have enjoyed my time more if I'd been better rested.

There are other train and bus providers taking passengers between Brussels and Berlin. But these journeys all required at least one change, and the quickest still took more than seven hours. At least by taking an overnight train, I wouldn't be wasting precious daylight hours of my trip just sat on a train.

The journey back a few days later was equally lacking in sleep. I took the 10:56 p.m. European Sleeper from Berlin, and after my busy weekend I expected to sleep like a log. But the bed I had booked had been downgraded to a seat because of problems with the train's toilets and electricity supply, and once again I found myself unable to sleep.

In my compartment I was joined by a family of four, and felt like I was intruding on their vacation. They struggled to sleep, too: The mother ended up sleeping on the floor between the two rows of seats in our compartment. I followed her lead and tried to do the same, but it didn't work for me.

Some passengers struggled to find their seats because the carriages weren't in numerical order, and multiple bathrooms were out of order.

I repeated my routine: Ear plugs, travel pillow, sleeping pill, and eye mask. And yet again, I got less than five hours' sleep by the time the train pulled in shortly before 11. a.m..

But at least this time I had a proper layover in Brussels. I had around six hours to look around the city, and this was enough time to justifying paying the nine euros (about $10) to leave my big backpack in a locker at the station.

The Eurostar journey back was much more pleasant. I ended up getting a Standard Premier seat, which was only £10 (about $13) more than a regular seat, and included a meal and a smaller carriage.

There were definitely some perks to traveling from London to Berlin by train compared to flying. I didn't have to pay extra for my bags and I could bring as many liquids as I wanted. The layover meant that I had the chance to explore Brussels, too. And it was also massively better for the environment.

But it was slower and more expensive. Low-budget airlines like Ryanair offer return flights between London and Berlin for under $100, and they're less than two hours each way. Yes, you do have to factor in how airports are outside the city center, taking a while to get to, and often transport providers add an airport surcharge, but for journeys like this where there is no direct Eurostar route they're still much more convenient.

In total, my four train journeys cost me around $650, though I'm set to get around $180 in refunds to cover the Eurostar delay and the European Sleeper downgrade.

Overall, my journey was tainted by an unfortunate set of circumstances: The Eurostar being delayed, not having a bed on either sleeper train, and many of the bathrooms being broken.

If I'd traveled a week later, I may have had an entirely different experience.