Most of us have at least some firsthand experience with insomnia symptoms. Sometimes you find it tough to fall asleep or you’ve awakened repeatedly throughout the night. Perhaps there are mornings when you wake up very early, unable to return to sleep—or you wake up feeling exhausted before you've even started your day.
Most people think of insomnia as a night disorder, albeit one that can significantly affect our daytime lives. For a long time scientists thought of insomnia in a similar way—as a nighttime disorder with consequences for quality of life, health, productivity, and safety. That’s changing, as emerging research indicates that insomnia isn’t something that happens only at night but a condition that plays out over the entirety of night and day.
On alert, day and night
Recent studies show that some physiological characteristics of insomnia, characteristics already known to exist at night and during sleep, are also present throughout waking hours. This research is contributing to a shift in the way scientists and sleep specialists think about insomnia, toward a new understanding of this sleep disorder as a 24-hour condition. Increasingly, science is paying attention to the waking physiology of insomnia.
A team of researchers from The Netherlands, Germany, and Switzerland investigated the brain activity of people with insomnia disorder during wakeful, resting states. This study included 94 participants, most of them female, between the ages 21 and 70. All had insomnia disorder, and candidates were screened to rule out other conditions, including other sleep disorders, as well as neurological or psychological conditions.
Using EEG, scientists measured brain activity during waking but restful states, both with eyes open and eyes closed. Compared to a control group without insomnia, people with the sleep disorder displayed greater levels of arousal, as measured by brain wave activity. People with insomnia showed less powerful alpha-wave activity and more powerful beta-wave activity.
An alert brain
Beta-wave activity in the brain is a sign of neurological activity and arousal. These brain waves are connected to mental and cognitive engagement, to alertness and wakefulness. Greater beta wave activity indicates a brain that is attentive and alert, and a mind that is engaged. Alpha waves are indicators of the absence of arousal, of a brain—and mind—significantly more at rest.
Increased power in beta waves, as well as other altered brain-wave activity, has been documented in people with insomnia during sleep. Scientists believe this hyperarousal of the brain contributes to the difficult nighttime sleep patterns of insomnia: Trouble falling asleep; restless sleep throughout the night; early waking; and the unrefreshed quality of sleep.
The identification of this increased beta-wave power during wakefulness suggests that the hyperarousal associated with insomnia at night is also present during the day. Other recent research has returned similar findings, which show the effects of insomnia-related hyperarousal in the way people seek treatment for the disorder.
In a recent study investigating prescription sleep aid use among people with insomnia, scientists at the University of Michigan found evidence of increased waking anxiety and alertness among people with the sleep disorder. The study included 649 adults, a majority of them women, who were all diagnosed with insomnia disorder. Researchers collected data about sleep disturbances, daytime alertness, depression and anxiety, as well as use of prescription sleep aids. The scientists followed up with participants after one year to collect data on the same subjects.
Nearly 20 percent of insomnia patients were using prescription sleep aids at the start of the study—and a majority of those people, 69.4 percent, continued to use sleep medication a year later. Scientists found that daytime alertness and anxiety both predicted the use of prescription sleep medication. In fact, daytime alertness and anxiety were the only predictors of prescription sleep aid use that scientists identified. Their analysis also found that as levels of daytime alertness and anxiety increased, so did the likelihood of chronic use of prescription medication for sleep.
These medications weren’t particularly effective in reducing insomnia. Insomnia patients who used prescription sleep aids showed no significant improvement to their sleep at the one-year follow up compared to people with insomnia who didn’t take sleep medication.
Hyperarousal linked to insomnia begins early
There’s also new evidence that the 24-hour presence of hyperarousal associated with insomnia exists in the brain as early as the teenage years. Researchers at Pennsylvania State University studied beta-wave activity among a group of 44 adolescents, some with insomnia and some without. They found greater power in beta waves among adolescents with insomnia—when the teenagers were asleep, and also when they were awake.
One interesting detail from this study: Those adolescents with insomnia who experienced the shortest sleep duration—who slept less than normal amounts—showed the greatest degree of hyperarousal during sleep and wakefulness, more so than adolescents with insomnia who had normal sleep duration. Researchers posit that this difference in arousal may help to explain the sleep complaints of people who experience insomnia, yet sleep for durations that are considered normal.
An around-the-clock model of insomnia
This group of recent studies creates an evolving portrait of the most commonly diagnosed sleep disorder. They demonstrate insomnia as a condition with altered neurological activity that transpires not only at night but also around the clock. In particular, these studies suggest that hyperarousal, which has for some time been associated with the sleep and nighttime physiology of insomnia, occurs throughout the waking day as well. The relationship between arousal levels in the brain and insomnia appears to start at a young age. And the elevated, round-the-clock arousal—as well as the anxiety that may frequently accompany it—appears to be a significant factor leading people to prescription drug treatment for their sleep problems.
We should expect to see a lot more research investigating the neurological and other physiological characteristics of insomnia that exist during states of wakefulness. With that research, and a more thorough understanding of insomnia’s mechanisms and broad reach, we may also discover significantly more effective ways to treat the condition.
Michael J. Breus, PhD
The Sleep Doctor™