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Mobile phones affect brain waves in bed
Judy Skatssoon
ABC Science Online
Tuesday, 28 March 2006
Chatting on a mobile phone before sleep affects the electrical activity of your brain.
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.
Mobile phones affect brain waves in bed
Judy Skatssoon
ABC Science Online
Tuesday, 28 March 2006
Chatting on a mobile phone before sleep affects the electrical activity of your brain.
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.
