Twenty or thirty years ago in England, the Arts Council put up a prize for a literary work written under the influence of drugs. It was rather spoilt by people claiming "Aspirin". Anyway, that occurred to me when I read (page vii of the Introduction) that this novel was written in 1933 on "two bottles of wine per day" which is quite a lot even for the hardened drinker Jean Rhys had become - she was in her early forties when she wrote this book.
You can see how the alcohol may have been effective. It's very hard to find good examples of Expressionism in literature, whereas in art it's very easy to compare and contrast Impressionist and Expressionist works. But this novel is an expressionist work, using (for example) colour imagery like splashes of colour and deploying dialogue in strong and bold strokes. Almost inevitably, it's short (152 pages) - expressionism is not about fine details.
And the alcohol was surely indispensable in overcoming fear of the censor and - perhaps more important - self-censorship. It cannot have been easy to write in 1930s England and in the first person about having sex for money or having an abortion when it was illegal.
The work still reads as very fresh - one might say, vibrant. It's an impressive novel.
Jean Rhys published several works in the 1920s and 1930s, none of them really successful. Then she disappeared from English literary consciousness until at the age of 76 she had great success with Wide Sargasso Sea (1966). Apparently, there were people who were surprised by the novel because they thought she was dead - something which I suppose was possible in the days before Google and probably reflects the fact that she did not attend London literary parties but instead was "living reclusively in Cornwall", which is no way for a living novelist to behave.