susanblackmore | Every year, like a social drinker who wants to prove to herself that she's not an alcoholic, I give up cannabis for a month. It can be a tough and dreary time - and much as I enjoy a glass of wine with dinner, alcohol cannot take its place.Some people may smoke dope just to relax or have fun, but for me the reason goes deeper. In fact, I can honestly say that without cannabis, most of my scientific research would never have been done and most of my books on psychology and evolution would not have been written.
Some evenings, after a long day at my desk, I'll slip into the bath, light a candle and a spliff, and let the ideas flow - that lecture I have to give to 500 people next week, that article I'm writing for New Scientist, those tricky last words of a book I've been working on for months. This is the time when the sentences seem to write themselves. Or I might sit out in my greenhouse on a summer evening among my tomatoes and peach trees, struggling with questions about free will or the nature of the universe, and find that a smoke gives me new ways of thinking about them.
Yes, I know there are serious risks to my health, and I know I might be caught and fined or put in prison. But I weigh all this up, and go on smoking grass.
For both individuals and society, all drugs present a dilemma: are they worth the risks to health, wealth and sanity? For me, the pay-off is the scientific inspiration, the wealth of new ideas and the spur to inner exploration. But if I end up a mental and physical wreck, I hereby give you my permission to gloat and say: "I told you so".
My first encounter with drugs was a joint shared with a college friend in my first term at Oxford. This was at the tail end of the days of psychedelia and flower power - and cannabis was easy to obtain. After long days of lectures and writing essays, we enjoyed the laughter and giggling, the heightened sensations and crazy ideas that the drug seemed to let loose.
Then, one night, something out of the ordinary happened - though whether it was caused by the drug, lack of sleep or something else altogether, I don't know. I was listening to a record with two friends, sitting cross-legged on the floor, and I had smoked just enough to induce a mild synaesthesia. The sound of the music had somehow induced the sensation of rushing through a long, dark tunnel of rustling leaves towards a bright light.
I love tunnels. They come on the verges of sleep and death and are well known in all the cultures that use drugs for ritual, magic or healing. The reason for them lies in the visual cortex at the back of the brain, where certain drugs interfere with the inhibitory systems, releasing patterns of circles and spirals that form into tunnels and lights.
I didn't know about the science then. I was just enjoying the ride, when one of my friends asked a peculiar question: "Where are you, Sue?".
Where was I? I was in the tunnel. No, I was in my friend's room. I struggled to answer; then the confusion cleared and I was looking down on the familiar scene from above.
"I'm on the ceiling, " I said, as I watched the mouth down below open and close and say the words in unison. It was a most peculiar sensation.
My friend persisted. Can you move? Yes. Can you go through the walls? Yes. And I was off exploring what I thought, at the time, was the real world. It was a wonderful feeling - like a flying dream, only more realistic and intense.
The experience lasted more than two hours, and I remember it clearly even now. Eventually, it came to seem more like a mystical experience in which time and space had lost their meaning and I appeared to merge with the universe. Years later, when I began research on out-of-body and near-death experiences, I realised that I'd had all those now-familiar sensations that people report after close brushes with death. And I wanted to find out more.
