Mobile Phones Affect Brain Waves In Bed
ABC Science
Journalist: Judy Skatssoon
March 28, 2006
Radiation from mobile phones stimulates brain activity in the early
stages of sleep even after you've finished using the phone, an
Australian study shows.
Associate Professor Andrew Wood from the Brain Sciences Institute at Melbourne's Swinburne University
says his study also found that exposure to electromagnetic radiation
from mobile phones can reduce levels of the hormone melatonin, which is
connected to the body's sleep-wake cycle.
But the study, reported in the International Journal of Radiation Biology, says it's premature to conclude that talking on your mobile phone before bed will get in the way of a good night's sleep.
Alpha waves
The
study's 55 participants received 30 minutes of mobile phone radiation,
or 30 minutes of 'sham' radiation, on successive Sunday nights before
being tucked into bed.
Wood found that exposure to mobile phone
radiation resulted in heightened alpha-wave activity in the brain.
Alpha waves are associated with relaxation and daydreaming but normally
disappear with sleep.
"We found that in the first hour or so
after getting to sleep that there was a significant change in one of
the parameters of brain activity, that is the amount of alpha waves in
the brain wave patterns," he says.
The increase occurred in the
first non-REM period of the night, when subjects had drifted off but
before they were in deep sleep.
Australian sleep specialist Professor Leon Lack, from Flinders University
in Adelaide, says this could be a sign that the first non-REM period of
sleep isn't as efficient as it could be, leaving people feeling tired
when they wake up.
"Alpha waves are really only present when you're lying awake with your eyes closed trying to fall asleep," he says.
"If
they are occurring during what would normally be sleep stages [it could
be] the intrusion of some sort of wakeful brain activity at a time when
it shouldn't be there."
Melatonin
Researchers also
tested participants' urine for markers of the hormone melatonin, which
is produced in the evening and is associated with individual sleeping
and waking rhythms.
Wood says some participants had an increased amount of melatonin after exposure, although there was no overall increase.
"Some
people had significantly less of this melatonin marker in their urine
before they went to bed but overall the amount of melatonin didn't
change," he says.
He says the difference was quite marked in
some people, indicating there may be "a special subgroup of the
population that are susceptible to the effects of mobile phone
radiation".
Lack says melatonin's role in sleep is unclear and it's uncertain whether having more or less affects your sleep.
Wood
says that at this stage mobile phones don't seem to influence how well
you sleep, unless the phones ring at all hours or you've had a
particularly exciting conversation.
"If people are finding they
can't sleep after using mobile phones often it's the content of what
they've been talking about that's the reason they can't sleep," he
says.