For some years I was happy not to even try and deconstruct or interpret Eraserhead. It didn't seem to matter what was going on underneath the surface – Eraserhead was about the experience of watching and listening and feeling the film, not the story or the subtext or the reasoning. Like a much loved painting or sculpture, it was enough to every now and again revisit the galley and let the work just wash over me. It is this very element, I would argue, that gives the film its multi-play longevity. But sooner or later, as with any work of art, you grow accustomed enough with its structure to feel the need to dig deeper, to speculate on what the various elements, surely not as random as they initially seem, actually mean. Certainly there is a sense of being pointed in a very specific direction by the central narrative, and this has been read by many as autobiographical on Lynch's part, a reflection of feelings and fears over his own domestic situation.

1967 was a big year for the young David Lynch. A student at the Pennsylvania Academy of Fine Arts in Philadelphia, he married his girlfriend and fellow student Peggy Reavey after she became pregnant with his child. Peggy herself admits that he was a reluctant father ("but a very loving one"*), and Lynch's art at the time took a noticeably darker turn, his painting The Bride featuring the abstracted figure of woman aborting her own child. Jennifer was born the following spring, and that same year Lynch made his first short film, The Alphabet, an unsettling play on the sounds and images of childhood and featuring the distorted cries of his own, new born baby.

Work on Eraserhead began just three years after daughter Jennifer's birth, but Lynch admits that he has no recollection of just when the idea first came to him, or even when he first wrote the script. About to invest considerable time and effort into a project that may never help to pay a single bill or even launch him on a career that would enable him to do so in the future, the young Lynch was facing the prospect of raising a family that he may struggle to both support and be able to devote the appropriate amount of time to. Even Jennifer Lynch herself, when questioned on the film, has suggested that the baby may have been inspired by her, and acknowledged that a popular reading of the film was a reflection of her father's fear of parenthood.

Think about if for a minute. Henry is living in virtual squalor, clearly unable to afford anywhere decent to live but making enough to to provide the bare essentials. Then his girlfriend gives birth and he has to support two extra mouths on the same meagre wage that had proved barely adequate for his own needs. The baby, when it arrives, is a monster. It spits out food, it cries all night, it gets sudden and inexplicable diseases and it begins to destroy Henry's relationship with his wife, who now twitches with revulsion if he even lays a hand on her. When Mary runs off to her mother's, the baby effectively nails Henry to the apartment, preventing him from leaving its walls and even laughing mockingly at his predicament. This is a vivid realisation of fatherhood and family life at its most wretched.

One night, as Mary thrashes about in an agitated sleep state and almost ejects Henry from the bed, we glimpse a woman who bears little resemblance to the one Henry married, her face worn and her mouth and eyes the source of peculiar noises. To his horror, Henry discovers that she is also producing, from somewhere in her lower body, a string of the embryonic creatures identical to the one in the film's opening sequence. What were then symbols of Henry's own ability to perhaps unexpectedly procreate (there is an unmistakeable sperm-like aspect to their shape) becomes a reminder of Mary's ability to do likewise, repeatedly if necessary, producing yet more horrible creatures to lie screaming on the table. No wonder, then, that Henry's first fantasy involving The Lady in the Radiator has her gleefully crushing the life out of the creatures with the heel of her shoe.

The scene in which Henry visits Mary for dinner is a nightmare version of an often horrible moment in many a young man's life when you first meet the girlfriend's family and are judged by people you have never met using mysterious criteria on territory that is effectively alien. The awkward embarrassment of this situation is captured perfectly here, not least in Henry's spectacularly uncomfortable seating posture, but the whole thing moves into the genuinely surreal at meal time, when Lynch plays with images of birth, sex, menstruation and the adolescent fantasy/fear of a come-on from the future mother-in-law.

When their relationship later falters, Henry is tempted into infidelity by The Beautiful Girl Across the Hall, a liaison that is again almost disrupted by the wailing, life-changing child. As the two descend slowly into a milky-white pool of sexual bliss, light once again gives way to dark, as Henry finds himself on the home territory of the Lady in the Radiator, whom he finds himself unable to physically touch. Instead he becomes victim to his own personal terrors, which concludes with his decapitation and the transportation of his head to a pencil factory, where it becomes the raw material for pencil-top erasers. You see, there IS a reason for that title. I'm not going to even TRY to deconstruct this sequence, but will note that it features a rare screen appearance by actor Darwin Joston, so memorable as Napoleon Wilson in John Carpenter's Assault on Precinct 13.

Back in Henry's version of the real world, our hero clings to the hope of a further meeting with his attractive neighbour and sits listening, dressed in his best clothes, for the elevator that will announce her return. When it finally happens Henry opens his door to be greeted by the woman and her latest companion, a virtual caricature of salacious, middle-aged sleaze. If she'll sleep with this guy, she'll sleep with anyone, the final nail in the coffin of Henry's self esteem. As her apartment door closes on Henry's prying eye and all hope of a future with her, the baby laughs mockingly and him. This is the crucial moment for Henry. He has lost his wife, his independence, his sense of self, and all because of the arrival of this malformed creature, which becomes the focus for all of Henry's resentment and failure and fear and leads to a notorious finale that is without question the film's most subtextually disturbing scene, as well as its most graphically horrific.

Driven by a mixture of cat-killing curiosity and pent-up frustration, Henry attempts to cut off the swathe of bandages that envelop the creature's lower body, only to discover to his horror that the bandaged ARE its lower body. As the skin splits and blood spurts from the baby's mouth, Henry thrusts the scissors into the exposed organs, an act of instinctive revulsion as much as a half-hearted attempt to finish what he inadvertently started. It's a story pulled straight from the headlines, that of a father who overreacts to the cries of his child and strikes it, but does far more damage than he could ever have intended. But Lynch takes this one horrific stage further – Henry hasn't hit his child, he has mutilated it.

As the baby's head grows to gigantic proportions and looms in the darkness over the cowering figure of Henry, a physical representation of his guilt, the Man in the Planet loses control of his machinery and by turns the man under his power. The planet itself begins to disintegrate. Finally, in a blaze of white, Henry is united with the Lady in the Radiator and the two embrace. Is this fantasy or reality or the afterlife? Have Henry's actions driven him mad or to suicide? Who's to say. But as the Lady in the Radiator so memorably and musically assures us earlier, "In Heaven, everything is fine."

Of course absolutely every word of the above could be complete hogwash. This is just one possible reading of a text that is open to impossibly wide interpretation, and this only covers a fraction of its dense layering. Are the mounds of earth and bracken that sit in Henry's apartment (and, if you look closely, Mary's house) just a reflection of Lynch's love of the organic, or do they have a deeper meaning? What of the small, grub-like creature that is left in Henry's mailbox and crawls in and out of the holes in the wall, expanding in size as it does so? And just why is Henry's head turned into pencil erasers? Like everything else, it's purely for you to decide. It's one of the most endearing qualities of Eraserhead that even when you don't know what's going on, it makes a sort of perverse sense. And that, surely, is the very essence of dreams.

* Quoted from Lynch on Lynch, revised edition, Faber & Faber 2005, edited by Chris Rodley.