Haim are sat in a hotel room in London’s Kings Cross and a fire alarm is going off. The building isn’t ablaze, they reassure me when the sudden and excruciating loud burst of alarm begins, it’s just a practice run. It’s a small thing to reassure someone when something unexpected happens, but it’s representative of the sort of people Este, Danielle and Alana Haim are. They look out for people.

After their emergence in 2012, the L.A.-based trio hit the big leagues with their debut album, 2013’s Days Are Gone. It sounded like nothing else at the time – rhythmic rock with pop sensibilities and an 80s R&B bite – and its influence can still be felt weaving its way through today’s musical landscape, with everyone from Dua Lipa to Troye Sivan adopting their music’s mix of the frenetic and the (often cheesily) playful.

While working on follow up Something To Tell You, though, the band experienced a period of intense difficulty. Aside from the expected second album syndrome, Danielle’s partner, the producer Ariel Rechtshaid, who has worked closely with the band since the beginning, was diagnosed with testicular cancer. The album was put on hold while he underwent treatment, before being finally released in 2017. “A lot of things happened between those two records that were out of our hands,” Alana explains. “It took us a moment to get through an interesting time.”

That period and its effects on the band, as well as their subsequent tour and just plain old growing up, make up the themes of the band’s upcoming as-yet-untitled third album. It comes following a burst of creativity that reminded them of first starting out a band and which resulted in a sonic shift for the group. The first single released this year was the breezy “Summer Girl”. With a knowing nod to Lou Reed, the song is perhaps the most relaxed the group has ever sounded, and it really suits them. That track was followed by the brilliant “Now I’m In It” and, most recently, “Hallelujah”, a song that leans into the band’s penchant for gloriously saccharine sentimentality.

At the heart of this new music, however, is the solidifying of each sister's individual selves as well as their sisterhood collectively. It’s music that overflows with love, assertiveness, kindness, strength and consideration.

Hello Haim. You’re starting a new album cycle. How do you decompress after an era?

Alana: It's an interesting process. We always talk about after-tour depression. I feel like when you're on tour, you're always going. But when you get back from tour you wake up and you're like, what city am I in? Then you realise that you're in your bed and that there is no show that night. When you start tour you go from 0 to 100. When you're done with tour you go from 100 to 0 overnight. It takes a really long time for your body to figure out what's going on and I feel like I chase the high of tour for the first four weeks after it finishes. I'll just be outside trying to find something to do. Then you get super sick and spend time in bed.

Este: You always get crazy flu after.

Alana: But it's the best process. And I think coming into new music, we really needed a little bit of time to sort out our feelings and our ideas. To decompress, which is literally just sitting and being with yourself, because on tour you're always surrounded by people and fun activities. I think sitting with yourself is the most important thing you can do, but also the scariest thing because you're alone with your thoughts.

I know after the first record there was a longer break than anticipated, so it must be interesting this time around to be coming back into it so quickly.

Este: I like it this way better.

Alana: With the music that is coming out now, we're just writing it and putting it out, which we've never really done before. I mean, we did it a bit with our first record because we didn't really know what we were doing.

How does the creative process change when you're releasing music that way?

Danielle: I think we're still figuring it out. I think, honestly, we're just trying to write and create things that we are inspired by in the moment, and not really caring about how it's going to fit on a record, which is kind of fun.

Alana: I think our favourite records are kind of like that, too.

Danielle: I think we want it to be cohesive, but we're not super stressing about it.

Did you have demos that you had written while on tour?

Danielle: “Summer Girl” wasn’t even a demo. It was something I had on GarageBand. I don't go anywhere without my phone, and people think I'm a spokesperson for GarageBand, but I'm not.

You use it on your phone?

Alana: It's really easy to use – you should try it.

I couldn't, not with my sausage fingers.

Este: You and me both, my friend.

Danielle: But it's actually easier than you think. I just sit and make little demos. I have “Summer Girl” on here. [Plays demo]. I basically had this a couple of years ago and I thought there was something to it. In April, I think it was, I was in the shower and remembered that cool thing I had worked on a couple of years ago. I took it to [producer] Rostam [Batmanglij] and he was like, “Wait, I hear something.” We started putting things on top of it and truly, that day, the song was put together.

But writing is like muscle for us – a lot of the time you have to do it. And these moments only happen so often, when you have an idea and you play around with it. I think that when we really sit down and try and write songs, that's when you kind of have to force it out.

It becomes work.

Danielle: Yeah. You have to sit down and say, ”Okay, we're going to write a song today”. It might be shitty but as long as we get something on paper, that'll be our work for the day. After a week we'll have seven random things and out of that there'll probably be one good idea.

“Summer Girl” feels like it’s about the healing power of love. Is that something you believe in?

Alana: 100%

Este: I believe in Celine Dion, so I also believe in the power of love.

Alana: And love can take on so many different things. It's not just with a boyfriend or partner, it's also self-love and the love that I get from these two peeps next to me. We talk about that a lot, and there's a song called "Hallelujah" that we have. It's one of my favourites and it's about that love that we have. It's so weird talking about "Hallelujah" with [Este and Danielle] next to me. I feel like it's too gushing. Like, eww. But it goes through how important it is and how lucky I am to have the love of my sisters. It feels like you're going to use this against me when we're in a fight or something [laughs].

Can you tell me about your second single "Now I'm In It"?

Danielle: People listen to it and think it's about a relationship and I get that. But we actually wrote it coming out of that tour depression. It's a story about being super in your head and being in a down place and waking up and not wanting to get out of bed and having crazy thoughts. It probably has to do the most with me and tour and the last couple of years that I've had. I crashed. It was hard. I think "Now I'm In It' speaks to just accepting that you're in a dark place. I think it's the moment that you accept it when you can start to get out of it in a way.

What did accepting it look like?

D: Well, talking about love – sisterly love – it was my sisters who said I needed to go to therapy. Before, I had been saying, "It's fine, it's fine. It's just after-tour depression." I ended up going to therapy and now I'm in a better place. That's what "Now I'm In It" speaks to.

I advocate therapy. I think everyone could benefit from it.

E: It's the best thing. Mental health is so important. I suffer from depression, I'm on an SSRI and I'm so thankful that I have that and that I'm dealing with it head on. I denied it for so long. At first I was in therapy twice a week. After tour I needed my "me time", but with a therapist.

Well it is kind of "me time" but just having someone there to help you understand you.

E: It helped me learn a lot about myself and how I deal with things. I think tour is part of what helps with it, in a weird kind of way, but it also bites you in the ass. You can't really run away from things. And I feel like sometimes when we go on tour it's like we can leave our problems in L.A., but the thing is those problems follow you. And I know for me – and thank God I have Danielle and Alana – I'm diabetic and travelling and touring with diabetes can be really hard mentally and with sleep and food. It can be a really dangerous disease when you don't take care of it, and I'm dealing with the repercussions of that now. But the good news is that with therapy and sisterly support, we've been able to get through a lot together.

Alana: I swear our record isn't super depressing [laughs]. But it's important. I think we like writing songs that are about things that are really hard to talk about, but we also want people to dance. It's a crazy push and pull with what we can accomplish.

Este: It's song about depression under the guise of dance song.

I call them melancholic bops.

Alana: I love a melancholic bop.

Haim's third album is set for release in 2020. "Hallelujah" is available now.