That's men for you: We will probably never know just how many men cut, burn or otherwise harm themselves to reduce distress or relieve tension.
The behaviour may seem bizarre but it is by no means rare. Have you ever punched a wall or driven recklessly in anger? Did you ever drink a huge amount of alcohol because of emotional pain? These are all forms of self-harm.
For some, though, self-harm becomes a regular, daily or weekly occurrence.
It is thought that this behaviour is more common among women and especially among young women than among men.
But women are more likely than men to admit to it, so the level of self-harm among men is more hidden.
Means of self-harm, in addition to those mentioned above, include banging your hand or head off an object or deliberately getting into fights with a high risk of injury.
Some of the people who behave like this have been bullied at school or abused in the home. Others may have learned to self-harm to cope with the stresses and strains of adolescence. Still others may feel detached from their own bodies, due to abuse or trauma, and self-harm provides a form of connection.
There is some evidence to suggest that people who self-harm are able to block out physical pain while doing it - but the pain returns quickly afterwards.
A person who learns to deal with stress by self-harming may end up using this behaviour in normal situations. A disagreement, a job interview, perhaps an upcoming journey, can all produce stress which, in turn, is dealt with by cutting or another form of self-harm.
Ending the behaviour can be difficult. A first step is to talk to somebody you can trust. This might be a GP, a teacher, a friend or a counsellor.
Those who deal with self-harm issues say that being able to talk freely and confidentially to somebody about it can be very effective.
As with all addictive behaviours, you may have to make many attempts to stop.
Giving up a behaviour is one thing: staying away from it is quite another.
Again, as with all addictive behaviours, it is important not to become discouraged when you find yourself relapsing. Keep trying to seek the help you need.
Although people who engage in self-harm are at a greater risk than others of committing suicide, self-harm is not generally a form of attempted suicide.
It is really an attempt to cope with the pain of living. To be more accurate, perhaps, it is an attempt to cope with painful feelings.
Neither is self-harm necessarily a form of attention seeking. So much self-harm is hidden from family and friends that, as a way of seeking attention, it would be most ineffective.
We all turn our anger against ourselves from time to time and we all seek ways to avoid experiencing hurtful feelings. People who self-harm have just found one particular way of doing that.
But the way they have found is ineffective. It does not help them to face or resolve the feelings that create the tension which leads to the self-harm. And the self-harm itself is almost certainly a source both of physical pain and of mental distress to them.
Self-harm is also a poor substitute for making changes in your life which would remove much of the distress you now feel. Like many of the compulsive behaviours we engage in to cope with anxiety, stress or other emotional pain, it gives poor value for the price it exacts.
If you self-harm, it's really worthwhile to talk to somebody you trust as the first step towards ending this behaviour.
You can get some good information on self-harm by going to the excellent Mind website at www.mind.org.uk and typing "self-harm" into the search box. One of the items near the top of the list of results should be a comprehensive booklet which you can read online.
Padraig O'Morain is a counsellor accredited by the Irish Association for Counselling and Psychotherapy.