Micro sleep

Almost half of male drivers admit to
experiencing micro-sleeps at the wheel. What are
they? It's a "horrifying" statistic, according to road safety
charity Brake. Of 1,000 drivers it interviewed, 45% of men
admitted to micro-sleeping while driving, as did 22%
of women. But what does this mean? Micro-sleep is an episode of light sleep lasting five
to 10 seconds. The brain goes to sleep involuntarily
and it is more likely to happen in a monotonous
situation. People wake suddenly, often with a sharp
jerk of the head. "Your eyelids start drooping and you start to lose
contact with reality," says Prof Jim Horne, director
of Loughborough University's Sleep Research
Centre. "You're asleep for a few second, then wake
up, often with a jolt." This sudden head jerk is how people commonly
know they've had a micro-sleep as the brain doesn't
remember such short naps. "Sleep has to last beyond a minute or two for your
brain to remember it," says Prof Horne, who studied
driver tiredness for 10 years. "With micro-sleep, you
are just left with a feeling of not knowing if you are
coming or going." It is caused, unsurprisingly, by fatigue. If episodes
aren't tackled, they become more frequent and last
longer until you eventually fall into a proper sleep. A head jolt in dangerous or inappropriate
circumstances, like driving a car or in a meeting,
can sometimes prevent further episodes as the
shock and realisation of what has happened sends
adrenaline pumping through the body. Drivers are particularly susceptible as driving can be
monotonous. They are more at risk in the afternoon
as the body experiences a drop in energy levels,
also at night when a person is usually asleep. Young drivers are also more at risk because young
people need more sleep in general, so are more
impaired by sleep loss. It's estimated that almost 20% of accidents on dull,
major roads are sleep-related, according to the
Department for Transport. Drivers have no excuse,
says Prof Horne. "Sleep doesn't come from out of the blue. You can't
be driving along alert one minute and falling asleep
the next. There's always adequate time to realise
how sleepy you are." His advice, included in the Highway Code, is to
safely park then have a drink containing about
150mg of caffeine. It will not kick in for 20 minutes,
so have a 15-minute nap and then freshen up for
five minutes before continuing your journey.