It's quite something to be depressed on Prozac. It's proof that the human spirit, when determined and ruthless enough, can overcome all chemical inducements to bonhomie.

Andrew Solomon, in his elegant if overlong book on depression that I’m reading slowly, Noonday Demon, likens depression to ivy taking over a tree; smothering it, gradually stunting new growth until it gets to a stage that even if the ivy is cut at ground level, the tree doesn't have enough leaf-mass to regenerate.

That feels right, but for me it's more akin to convolvulus, or bindweed – that fast-growing weed with delicate white flowers that seems so pretty, but last only for a day. Trying to rid a garden of bindweed is next to impossible – for if you dig it out, each segment of root is capable of self-propagating – so the more effort you put in, the more you cut into it, the worse it gets. By first frost, the garden is covered with a dead brown matting of intertwined threads and tendrils. Then it is easily hacked off, the winter garden can be made presentable, and everything looks healthy again, if a little sparse. Come spring, and the flower-tipped shoots return with a vengeance, seductively entwining themselves around every stem.

At night, the flowers look particularly attractive. Depression is a night-feeling, of shadows and shades and increased sensitivity to compensate for limited sight. One's worldview becomes strangely like the image in the viewfinder of an infra-red camera – seeking out energy instinctively, the shapes one sees being primitive projections of one's own desires and compulsions, blurry Turin-like saviours, offering ghostly promises of redemption. Or is it confirmation of damnation? There is no light, no colour. A million shades of grey. A curious sixth sense emerges, fuelled by testosterone, where shadows take on the almost supernatural charge of symbol, and the world is ruled by a self-fulfilling prophecy: thou shalt encounter only those who are in the grip of the same neanderthal phallic Daddy-search, ready to lock antlers with the demons of your unconscious, primed for a futile unsatisfying scrap – unsatisfying, for the victory is against oneself. No real meeting happens. Or, the reality is of the bindweed kind – parasitic, suffocating, transient and overwhelming.

We see what we want to see; and those night-flowers of bindweed only last a day, but I can't get enough of them. I don't want to wake up and face the day, and deal with reality, for the light hurts my eyes, so used am I to seeing the murk in other people's souls.

Soul is the longing of the soulless for redemption, a friend of mine wrote in my Oscar Wilde fridge-magnet notebook, quoting someone he couldn't remember. Longing is the feeling I'm sitting with at the moment, if I stop running away from it and sit with it, which I am loath to do. I'd rather be involved in a nocturnal chase to confirm the ugliness of the world, to root out seediness and display it to demonstrate my perfectly-honed skills at night vision, at seeing what drives us all to destruction. Or to reconstruction, if we can manage to see beyond the symbolic death and see the birth that is imminent.

The other day I spent the day with a five-year-old boy – brought him to the park, bargained with him over sweets, scared him with my anger when he ran across a road, shopped with him and cooked him pizza, removing the pineapple bits for him. At lunch, he informed me gravely that he wanted to go to the loo, and I had to wipe his tiny little bum with toilet paper, skin too soft, asshole too small to leave anything but a baby snail-streak of shit. Later that evening, in front of the Muppet Pirate Movie video, he climbs up on top of me and starts stroking me, jiggling around on my body, hands stroking my stubble. I feel neither shame nor pleasure; just an awareness of terrible destructive power – an adult feeling. But this child's innocence soothes it, diminishes it.

He falls asleep when Tim Curry is let go into the darkness with the treasure in a leaky boat, his blond head on my arm, his body spooning against my torso. There is no escape then. I put him to bed, he squirms at the cold sheets, and then sighs and sleeps again.

There’s a new report on fathering out – at www.fathersdirect.com/media – which takes an overview of all the sociological and psychological research on fathers. It makes for encouraging reading – most importantly, it deepens our understanding of the nurturing and caring side of men, which is so necessary to balance the advances that women have made in the public realm. Among its findings are that men have equal sensitivity and reactions in heartrate and blood pressure to their crying or smiling children as mothers do – knocking squarely on the head the notion that women are biologically more suited to parenting. Fathers adapt and respond to children in exactly the same way when feeding them as mothers do – knowing instinctively how to match the infant’s needs. Fathers and mothers give their babies the same amount of affection. Many studies show that the closeness between baby and father is almost identical to that between baby and mother. Linguistically, men are just as capable as women in speaking to babies in a way they can understand – although men are more likely to use inappropriately complicated words. The report leaves it for us to decide whether or not this is a good thing – suggesting the possibility that it is through fathers that children stretch themselves linguistically, to try to understand them. The gender of parents is also irrelevant – same-sex couples have been studied, showing that it is more important that children have two carers (or more) than just one – the gender of the secondary carer is irrelevant in the child’s later development; kindness and warmth are more important. The quality of caring by the father is more important than the quantity of time spent with children. Where dads are around and supportive before the age of seven, children are less likely to lead a life of crime; where dads are around and supportive in the ages of seven-11, children are more likely to succeed at exams age 16. It is sad that the only scientifically measurable impact of fathering pre-adolescent children is whether or not exams are passed, but let’s not dwell on the limitations of science when it comes to evaluating the fruits of love.

Each generation of fathers believes that they have discovered the joys of fathering; being a father is cited as the most important thing in most men’s lives. Men have always been warm and kind – it usually takes a while for them to realise it, and to open themselves up.

I am not a father – nor am I likely to be, now. But there are children in my life, and I feel lucky. I’m the only man around in their lives – and so, without inviting it, I feel some sense of responsibility, although it’s a nebulous feeling. But their love for me is profoundly healing, the smiles on their faces when they see me are like a dawn chorus to my night-loving soul.