I scare people. Not that this deters my readers - overwhelmingly female - from buying my books. They relish the fact that they are, if they're lucky, going to be sucked into the world of my imagination where very bad things happen to innocent victims.

There is no shortage of readers for books that chill to the marrow, stories that leave us afraid to turn the light out at two in the morning, tales that turn our dreams lurid. And yet this week's British Crime Survey reveals that women - by far the majority of crime fiction readers - are increasingly afraid of becoming victims of crime. In spite of the fact that the crime rate is falling and that in most instances men are more at risk, we women are much more scared than they are of what's out there.

Why are we so fearful? What feeds our fears? And why, paradoxically, do we appear to seek out the very materials that feed our terrors?

There is no simple answer, for fear is a complicated emotion. More than the automatic and entirely reasonable response to danger, fear is often an irrational escalation from a seed of reality, but it is no less real to the person experiencing it than a reaction that has a valid basis.

The Home Office survey shows that women are far more afraid than men of certain kinds of crime: rape, physical attack, mugging, burglary, being pestered or insulted. The notion that they might be raped or sexually assaulted worries men far less than having their car broken into.

The crimes women fear most are those that strike at the heart of who we think we are. At a recent conference in London, female crime writers spoke of their feeling that it would be impossible to have their central characters survive a rape and continue a series of novels without seismic shifts in style, tone and content.

When I was a working journalist, I was the victim of an unprovoked attack at the hands of a well-known sportsman. He punched and kicked me. The physical damage he caused was no more than deep bruising, but the psychological damage was profound. It changed my view of who I was. I no longer felt safe doing a job I had previously known I was good at. I felt fear where before I had felt confidence. I didn't want revenge - I just wanted to hide away because at some level I couldn't escape the idea that, somehow, it had been my fault.

Such beliefs are reinforced by authority all the time. Judges who indicate that rape victims were somehow asking for it because of the way they dressed or where they were; police officers who warn women not to go out alone when a rapist or a killer is on the loose, imposing a curfew on the victims rather than the perpetrators; people who criticise those women who endure domestic violence rather than walk away.

All of this contributes to the insidious growth of fear. Culturally, in spite of the changes wrought by feminism, most women are still relatively powerless compared with men. And, whether consciously or subconsciously, it works to men's advantage to keep us scared.

Women are more likely than men to experience harassment at work and on the street. Once you have been harassed, it's a lot easier to imagine how that could escalate into something worse. And, of course, once you have been on the receiving end of violence, you are much more likely to live in fear that it could happen again because you know what it does to you. Women who have experienced domestic violence consistently report higher levels of fear in public places.

Sometimes, too, the response to violence against women seems wilfully lacking in sensitivity. The fear that if something does happen to you, it won't be taken seriously, also feeds into a general sense of apprehension and insecurity, and is the reason why so many women don't report minor or even major assaults.

Of course, when a survey like this appears, there is always a scurrying around to find an acceptable scapegoat. One easy target is the dramatisation of crime that takes place in the media and the arts. This is not without some basis in truth. One academic study found that in Britain, readers of tabloid newspapers with more sensational crime coverage reported higher levels of fear than those who obtained their news from the broadsheets. Most women I know won't turn on programmes such as Crimewatch UK because they feel they are designed to jack up viewers' adrenaline levels and make us more afraid.

Nevertheless, we still watch dramas like Without Reason, in which young women are abducted, abused and gruesomely murdered. We still devour serial killer thrillers in which women like us are regularly treated as disposable victims whose sole function in the novel is to be taken, tortured and terminated to satisfy the desires of yet another psychopath.

I like to think that I write rather more thoughtfully than that; tot up the victims in my 15 novels and you will see I'm pretty much an equal opportunities murderer. But I admit that when I write about extreme violence, I intend my readers to flinch. It's important to me that my portrayal of the terrible things people do to each other - and, believe me, the real world is infinitely worse than anything I have ever invented - is rooted in a reality in which violence really does hurt. My characters do get scared. And usually for very good reason.

So why am I - and my readers - colluding in the fear industry? I suppose one answer is that exposing ourselves to fictional material somehow reassures us. Whatever is happening, it's happening out there, to someone else. It's as if consuming this material has a totemic effect; it becomes a talisman to keep us safe.

But perhaps it is more to do with the undeniable fact that certain kinds of fear are actually pleasurable. Adrenaline is, after all, a fabulous drug. It produces a great high, it's legal and it's free. We love roller coasters, the steeper and faster the better. We adore horror movies. Though few of us would care to admit it, most people at one time or another fantasise about terrible and scary things happening to us.

Best of all, we know that if it's drama or fiction or our own fantasy, the outcome is under control. Order will be restored, reassurances offered. No human has been hurt in the making of this movie. However, it is an equally uncomfortable fact of life that being scared - especially if we can legitimise it to ourselves and others - is a very good tool for avoidance of responsibility and deflecting criticism. Whether or not we admit it, bringing out the protective element in others is a strategy that appeals to many of us.

Women's fear does, it seems, have benefits for both men and women. While that remains true, it's not going to go away.

• Val McDermid's latest novel is Killing the Shadows (HarperCollins).