Pseudoinsomnia is a sleep disorder, even though people who suffer from it appear to have perfectly normal sleep patterns. When pseudoinsomnicacs fall asleep every night, they feel as if they are lying awake, anxiously trying to get some rest. But they're not imagining things. They really do have an unusual form of insomnia.
In last week's issue of New Scientist, Ann Finkbeiner has a terrific article about the people who suffer from pseudoinsomnia, and a handful of scientists who are trying to figure out what their brains have in common. When they used conventional methods of analyzing the brain wave patterns of sleepers, it appeared that these pseudoinsomniacs were no different than any other sleeper. But then they tried something new. They analyzed the readouts of brain waves using an algorithm that's normally used for spectral analysis in physics.
And that's when they began to see a pattern — a pattern that suggested these peoples' sleep cycles were being interrupted by brain wave patterns associated with fear, anxiety, and wakefulness.
The first things it uncovered were subtle differences in the EEGs of sleeping insomniacs: alpha waves – signatures of wakefulness that are supposed to show up only in early sleep – were intruding into deep sleep. Alpha intrusions can often be identified even without spectral analysis. "It looks like a choppy wave on top of a crown-like wave," says [psychologist and sleep researcher Michael] Perlis. But Andrew Krystal of Duke University in Durham, North Carolina, used spectral analysis to quantify just how much they were intruding.
Krystal's non-sleepers not only had a greater proportion of these alpha disturbances, but the alpha waves were bigger and the delta waves were correspondingly smaller.
That wasn't all. When Perlis and other researchers applied spectral analysis algorithms to the EEGs of their sleeping insomniacs, they found different patterns, fast waves known as beta and gamma (Sleep, vol 24, p 110). Normally, these are indicators of consciousness, alertness and even anxiety ...
Like alpha waves, Perlis calls these beta and gamma waves "intrusions" into normal sleep: "It's as if somebody is playing with the switch – boop, boop – flipping at a mad rate between wake and sleep," he says. More studies confirmed the link between beta and gamma waves and pseudoinsomnia ...
Some researchers are trying to piece this together. The work is still in its early days, and like much of the basic science of sleep, is still unclear. But greater beta and gamma power – what Perlis calls a "gained-up system" – may mean that arousal levels are higher in the brain of a sleeping insomniac, says Richard Bootzin of the University of Arizona. In other words, their problem is not so much that they don't sleep but that, asleep or not, their brains are never quite off. "It's the major hypothesis of what insomnia's about," he says.
Researchers are beginning to turn to the "always-on" hypothesis to explain forms of chronic insomnia beyond Rennik's group. Earlier this year, a study by Rachel Salas at Johns Hopkins University in Baltimore, Maryland, and her colleagues revealed fundamental biological differences in the brains of all insomniacs.
Around the clock, awake or not, their subjects' brains showed enhanced activity compared with normal sleepers. One surprising consequence was that they picked up simple new tasks more quickly than their well-rested counterparts.
What's fascinating is that similar patterns of alpha, beta and gamma waves show up in the brain wave patterns of people who suffer from chronic pain and anxiety as well. It's possible that this "always-on" brain pattern leads to a variety of nervous symptoms, including being unable to get the benefits of a healthy night's sleep.
Read the full article at New Scientist