Why Johnny Can’t Sleep
Bright monitors and action-packed video games are a prescription for wakefulness that lingers long after the computer is shut down.
By Sandy Keefe, RN, MSN
April 11, 2005
In many American households, computers have proliferated like pumpkins on a vine, linked by wireless networks or cable. Dad needs a telephone number to buy tickets to the next Lakers game. He sits down at the PC in the recreation room, types the business name into a search engine, and finds the number in 0.13 seconds. It’s time for Mom to renew her library books and place a hold on the CD version of John Grisham’s new courthouse thriller. Slide a finger across the touch pad to bring the laptop to life and click on favorites. Three minutes later, the books are renewed and the CD is reserved at the local library. Clicking on a different fave folder, Mom checks out the latest nursing news and selects an online continuing education course. Brother uses his laptop for online games that pit his manual dexterity and quick wit against teens across the country. And 6-year-old Sister wriggles impatiently, CD in hand, for a free computer so she can rescue pets in Barbie’s new veterinarian program.
Unfortunately, American families may be paying a steep price for this easily accessible technology, according to researchers from the Akita University School of Medicine in Japan. Playing an exciting CD game right before bedtime or lingering at the laptop to play one last video game can cause wakefulness long after the computer screen has gone blank. The bright light from the display, coupled with an exciting task, seems to interfere with the body’s production of melatonin and normal sleep-wake cycles.1
Melatonin, the hormone of sleep
Melatonin, commonly known as the hormone of sleep, is linked to light-dark cycles as well as sleep-wakefulness cycles. When the lighting level of the environment begins to dim, the hypothalamus and its neural pathways send messages to the pineal gland that trigger a release of melatonin. Just before sleep, melatonin serum levels increase 10-fold, with a peak around midnight. Twenty-four-hour melatonin levels are higher during winter than in summer. Melatonin production decreases with age, which may help explain the increased prevalence of sleep disorders in elderly individuals.
Shigekazu Higuchi and colleagues measured melatonin levels in the saliva, body temperature, self-reports of sleepiness, and relative theta power on EEG (a measure of sleep-readiness) in healthy male computer users.1 The men were asked to carry out either an exciting task (a video shooting game) or a boring task (simple math problems) on computers with either a bright or dimmer monitor display. They worked on these tasks on alternate nights between 11:30 PM and 2 AM, right before retiring for the night.
Research findings
Salivary melatonin levels increased at 2 AM under all conditions and were significantly affected by the brightness of the video display. When the screens were bright, men had higher melatonin levels when they were involved in the boring task and lower levels when they were engaged in the exciting task. However, melatonin production during boring tasks was essentially the same, no matter whether the screen was bright or dark.
Rectal temperatures went down at night in all circumstances, reflecting the normal circadian rhythms of everyday life. However, body temperature did rise during exciting tasks and was higher when the video displays were brighter. Likewise, heart rate decreased normally in all circumstances, but there was less of a drop during exciting tasks than during the boring ones.
Not surprisingly, the men described themselves as sleepier during the boring tasks than during the exciting ones. Relative theta power was also higher during these boring tasks. However, bright video displays did not impact the men’s self-reports of sleepiness or relative theta power.
Getting a good night’s sleep
Clearly, engaging in exciting tasks on a bright video display influenced the men’s melatonin production, body temperature, and heart rate. When the men were engaged in exciting computer tasks, their brains were not ready for sleep. Indeed, the researchers noted that 53.7% of Internet users in Japan have delayed bedtimes and that 45% of them had shorter sleeping hours.
To get a good night’s sleep, it seems that it’s best to limit computer use late in the evening. If that’s not possible, it’s a good idea to dim the screen and limit computer activities to those that are less than exciting. Brother’s competitive video game would be a bad idea, as would Sister’s interactive CD program. And Mom’s continuing education course? Well, that just depends on how stimulating it is!
Sandy Keefe, RN, MSN, writes frequently for Nursing Spectrum.
Reference
1. Higuchi S, Motohashi Y, Liu Y, Ahara M, Kaneko Y. Effects of VDT tasks with a bright display at night on melatonin, core temperature, heart rate, and sleepiness. J Appl Physiol. 2003;94(5):1173-1176.