THURSDAY, April 15 (HealthDay News) -- Parents who worry that their teenaged son won't sleep well if he indulges in a violent video game right before bedtime may be fretting needlessly.
A new study found that teens who played the popular video game "Call of Duty 4: Modern Warfare" took only slightly longer to fall asleep than teens who watched a documentary.
A report on the finding appears in the April 15 issue of the Journal of Clinical Sleep Medicine.
Australian researchers found that it took teens a median of 7.5 minutes to fall asleep after playing the video game, only slightly longer than the three minutes it took them to nod off after watching the Academy Award-winning March of the Penguins on DVD.
The video gamers were only slightly less sleepy than the documentary watchers following each activity, although they displayed a slight increase in cognitive alertness. The researchers found no significant differences in physiologic arousal between the two groups, and both ended up sleeping normally.
But the teens played the game under very strict conditions, ones that might be very different from what happens at home, explained lead researcher Michael Gradisar, senior lecturer in clinical child psychology at Flinders University in Adelaide.
"The teens only played the video game for 50 minutes, and they only played it on a single night," Gradisar said. "Despite finding that they were mentally stimulated playing the video game, I believe the 'dose' of 50 minutes was too low to have any major ramifications on their sleep."
The short amount of time also kept the boys from becoming too wrapped up in the action. "Being limited to 50 minutes didn't allow the teens to become emotionally invested in the video game," Gradisar said. "Thus, if their character died, it didn't matter."
The researchers said their study did not receive any funding from the video game industry.
The research involved 13 boys between the ages of 14 and 18 who normally fell asleep in less than 15 minutes.
The teens sat in bed beneath the covers with electrodes attached and lights dimmed, and were asked to either watch the documentary or play the video game for just 50 minutes before going to sleep. The 50-minute time period was chosen because it is the maximum amount of continuous play recommended by game marketer Sony Corp., according to the study. A week later, the same teens returned to perform whichever task they didn't get the first time around.
Eleven teens took longer to fall asleep after playing the video game than after watching the documentary, while two fell asleep faster. Four teens actually fell asleep during the documentary, a slow-moving and tranquil movie that was chosen to provide contrast to the frenetic video game.
Seven of the teens told researchers they felt less sleepy after playing the video game than after watching the documentary, while four indicated the same level of sleepiness and two felt less sleepy after watching the movie. When the teens slept, researchers found all slept normally with appropriate amounts of rapid eye movement (REM) sleep and slow-wave sleep.
"These results are a bit surprising, in that a stimulating activity right before bedtime did not alter teens' established sleep patterns. This is good news for parents," said Cheryl K. Olson, co-director of the Center for Mental Health and Media at Massachusetts General Hospital in Boston.
However, Olson noted that the study did not reflect the reality of teenage life, in which a multitude of media are all competing for kids' attention.
"This study was done under tightly controlled conditions that rule out other ways media can disrupt sleep," she said. "Other studies have shown problems with children using media instead of sleeping. They sacrifice sleep to spend more time watching TV, playing games or texting friends."
Gradisar agreed, noting that the 50-minute limit is one few teens would be expected to follow on their own initiative.
"We found that teens in our study were less sleepy after playing the video game compared to watching the documentary DVD, which suggests if they were left to their own devices, the teens would have chosen to continue playing the video game, which would have eaten into the beginning of their sleep opportunity," he said.
Teens might also play longer if they play a game more than one night, because they will become more emotionally invested in the game as their character progresses through the story, he added.
"So I guess the moral of this study, particularly for parents, is moderate your teens' video game playing," Gradisar said.
For tips on establishing good sleep habits for teens, visit the U.S. Department of Health and Human Services.