Half a page is devoted to diagrams of outdoor dens. There is a large section about a book of first-person testimonies from the last generation of British lighthouse keepers and their families.
The video artist Bill Viola, director Ingmar Bergman and author Raymond Briggs are recurring presences in different forms. Occasionally there are snatches of chords and lyrics. The notebook starts off playful, but gets gradually darker, more desperate. It becomes harder to ignore the dark, shadowy figures that appear sporadically, menacingly on the pages.
"There's loads of drawings of these big black beings standing over my bed watching me sleep," Khan explains. "That's how I was feeling doing the book. Everything I was doing, they were around, these ghouls that are chasing you or just always present and leave behind this sense of uneasiness." She pauses. "At least that's how it feels sometimes."
You don't need to be trained in psycho-analysis to decipher what these unnerving creatures might represent. The first Bat for Lashes album, the Mercury Prize-nominated Fur and Gold, came out in 2006 and announced Khan as a rare and subversive talent: not only did she write the songs and supply the dramatic, reverb-heavy vocals, she played most of the instruments and created a fantastical universe in which they existed.
Her sophomore effort in 2009 was the even more ambitious Two Suns, featuring Khan's blonde, femme-fatale alter ego Pearl. Against expectations, the album went to number five in the charts and proved that she could write a conventional pop hit, with Daniel winning an Ivor Novello award. Khan's look - flapper-era headbands, glitter, Native American threads - became pervasive with girls who didn't look nearly as good in it as she did and Rolling Stone called her "the next Kate Bush". Not bad for an uncompromising concept album.
So, when it came to writing the third Bat for Lashes record, you can imagine that Khan might have been feeling a bit of pressure. Hence the shadowy monsters and increasingly fraught scribblings in her Moleskine.
"Stress! Stress! Oh God, oh God, oh God!" she says, leafing through the pages. "I was getting very stuck and having writer's block and getting panicked and really upset. I was honestly ready not to do music anymore because I thought, 'That's it, I'm just going to go off and have a baby. I don't want to do this any more.' I'd lost my way."
Having stepped away from music for a couple of months to clear her head, when Khan went back to her notebook, The Haunted Man started to take shape.
It would be an album about England, a love letter to Hertfordshire where she grew up and Sussex where she now lives. Without even realising it, the menacing creatures disappeared.
In line with any self-respecting, mid-career crisis, Khan decided to overhaul her image. Her long, flowing locks have been clipped into an orderly bob with a forbidding fringe and today she wears a simple vintage summer dress with just a dash of make-up.
"Maybe to other people it seems like I've tried to reinvent myself, but it's not in a Madonna-y conscious way," she says. "I don't want to go out wearing glittery headbands again because I did that seven years ago. And I want to cut my hair because people cut their hair in life, because it's hot in the summer having hair all down your back and sometimes your hair goes a bit crap."
The starkest expression of her new look is the cover of The Haunted Man.
Previous Bat for Lashes record sleeves have seen her surrounded by candles, holding a planet in each of her hands or even the face of Daniel LaRusso (yep, The Karate Kid) spray-painted on her back. This time, she is buck naked, standing assertively like a huntress with a man, also nude, draped over her shoulders. The image, shot by Ryan McGinley, is stunningly simple and unretouched; scandalously, Khan hasn't even bothered to shave her legs.
It's hard to predict how it will be greeted, but it already feels like an iconic piece of album art.
"I was looking at old pictures of Patti Smith and PJ Harvey, those raw women of the past, just not giving a shit," says Khan. "Or Frida Kahlo with her amazing eyebrows and moustache and I think that's a bit lacking these days: real bodies, real people. So I'm proud of that aspect of it.
"I did have a freak-out when it first came out," she says ruefully. "I'm only human; as much of me that is badass and like, 'Have it!' I'm still conscious of the fact that people are seeing something quite vulnerable and raw. But I remember thinking: I don't want to hide anymore, I want to step forward and be bold with this album and it's happened."
The boldness extends to more than the cover. Khan feels The Haunted Man is the most punchy and assured Bat for Lashes album to date. Although the genesis of the material was often dark and tumultuous, the result is unexpectedly upbeat and euphoric.
The singles, Laura and All Your Gold prove that Daniel was not a flash in the pan and overall Khan believes the record has an ambition and energy that is channelled more efficiently than before.
"I feel like I'm at the crux of something quite special," she says. "There's a feeling in the air which is different to the other two. I feel like I'm reaching something."
It's tempting to think that, in some ways, Khan has been spurred on by the breakthroughs of Adele and Florence Welch, or the continued excellence of Bjork, PJ Harvey and Joanna Newsom. "I do feel like I'm glad they're there, it's less lonely because of them," she confirms.
"It's reassuring to see their lives unfolding, like a distant family member or something. You know, when you're in a normal family and you feel like a black sheep? But then you've got a mad auntie who lives in France or somewhere and she sends you weird things and you think, 'Oh, it's all right. I'm not alone."'
Khan giggles, "It's a bit like that. When Bjork comes out with some mad new album, I think, 'That's good.' It's reassuring."
Who: Bat for Lashes aka Natasha Khan
What: New album The Haunted Man released October 19
Playing: St Jerome's Laneway Festival, Silo Park, Auckland, January 28
- TimeOut / Observer
