Mysteries of the Sleeping Brain



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From the Archives: A Neuroscientist Describes His Stroke



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Wake Up! The Science of Sleep

Photo courtesy of Rebecca Carlson/AAAS

Photo courtesy of Rebecca Carlson/AAAS

Why don’t people care more about sleep? We wake up early and go to bed late, and let our kids do the same, trying to put more “day” in our days, when it’s the nights that build our memories and heal our brains and the rest of our bodies.

The National Institute of Medicine has called sleep disorders and sleep deprivation “an unmet public health problem,” Michael Twery, director of National Center on Sleep Disorders Research, told an audience at the American Association for the Advancement of Science (AAAS) in Washington, DC, on Tuesday.

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World Science Festival: The Mind After Midnight

When I bought my ticket to Friday’s World Science Festival (WSF) event, The Mind After Midnight: Where Do You Go When You Sleep?, I didn’t think one of my main takeaways would be “birds are even cooler than I thought they were.” It’s not enough that they can fly, but did you know that some birds, such as the Bar-Tailed Godwit, can fly for several days without resting? And, that many birds (and some marine animals, for that matter) can sleep with one eye open?

According to Niels Rattenborg, group leader at the Max Planck Institute for Ornithology and one of the three scientists presenting at the WSF event, the first phenomenon is still in the process of being studied, although Dr. Rattenborg’s lab has issued a hypothesis that “some forms of sleep could well be compatible with flying.”

The Max Planck Web site notes,

Like mammals, birds exhibit two forms of sleep: slow-wave sleep and REM sleep (rapid eye movement). While slow-wave sleep can occur alternately in each of the brain's two halves, REM sleep always takes place in both sides of the brain simultaneously. During unihemispheric slow-wave sleep, the eye connected to the awake side of the brain remains open. This condition might allow birds to continue visually navigating while asleep. If it is not necessary for the birds to watch their environment continuously, a version of slow-wave sleep involving both halves of the brain should also be possible. The reduction in muscular tone that accompanies REM sleep makes it unlikely that birds experience REM sleep in flight.

In addition to potential navigation, Dr. Rattenborg and his colleagues have proven that some birds sleep with one eye open to detect predators. He described one experiment in which he literally put his ducks in a row and found that the two birds on either end kept the eye facing away from the group open while they were sleeping. He explained that the brain connected to the open eye can function in a half awake or drowsy state.

While humans obviously don’t have this ability, Rattenborg did note that parts of the human brain can sleep more deeply. For example, if one arm experiences a more rigorous workout, the brain area connected to that limb will experience a deeper sleep, he said.

Completely switching gears from birds to humans, another key takeaway at the WSF event was that sleeping can be dangerous for some people. Dr. Schenck spoke about extreme parasomnia cases such as sleep aggression, sleep terrors, and sleepwalking. He showed several videos of people exhibiting these types of behavior and told the much-publicized story of Ken Parks, a Canadian man who murdered his mother-in-law and attacked his father in law while asleep (he was tried and acquitted).

Parasomnias of this nature occur because the mammalian paralysis in REM sleep is not working, resulting in people acting out their dreams. Many diagnosed people have been successfully treated with the drug clonazepam, Schenck said.

And while the studies on parasomnia in and of themselves are quite fascinating, an eye-opening discovery has been the relationship between REM sleep behavior disorder (the category of parasomnia in which muscle paralysis does not work) and Parkinson’s disease (PD). According to Schenck, 81 percent of REM sleep behavior disorder cases convert to PD. He views this as an exciting opportunity for early intervention for PD, and explained that it is an area being researched by a collaborative international effort. 

–Ann L. Whitman

Dreaming of Henry Rollins

The Rubin Museum has officially kicked off its fourth annual Brainwave series, which pairs artists and scientists in conversations about the brain. This year’s theme focuses on dreams, and last night punk rocker turned spoken-word artist Henry Rollins opened up to neuroscientist David Eagleman, Ph.D. about the violence and anxiety that plague him in his sleep.

According to Eagleman, there is an over-misrepresentation of grief and misery in dreams. And, even more fascinating, dream content does not appear to be dependent on personal circumstance and environment. He noted a study by Susan Malcolm-Smith et al. at the University of Cape Town, South Africa, which compared the number of “threat dreams” experienced by the inhabitants of a sleepy town in Wales and to those of a high-crime area of South Africa. Contrary to predictions by the researchers, the number of threat dreams experienced did not significantly differ based on location.

Some lucky sleepers, Rollins included, have the ability to take control of their nightmares, forcing a more amenable outcome or prompting themselves to wake up. This state of mind, said Eagleman, which is somewhere between consciousness and REM sleep, is called lucid dreaming.

Rollins explained that he is sometimes able to get a “do-over” in dreams where he is back in a familiar dream, but this time has the ability to control the outcome. For those not naturally in possession of this ability, lucid dreaming is actually something that can be learned through training, said Eagleman. Upon assuming control of one’s dreams, “most people fly or have sex,” he quipped.

I’ve experienced the “do-over” type of dreaming that Rollins described, turning potential nightmares into more of an Indiana Jones-esque adventure.  But, my most memorable lucid dream, and possibly my first, is from my childhood. I dreamt that I was in the back of a taxi and decided to change the driver’s hair color several times. Maybe not the most exciting action in a dream world of endless possibilities, but at the time I thought it was pretty amazing.

The Brainwave event ended with a disclaimer by Eagleman that science still doesn’t know exactly how we dream and why, but, he said, it’s clear that the awake state and the asleep state find the brain in two completely different modes that are equally active.

To learn more about dreaming, the Rubin Museum’s Brainwave series runs through April 20.

–Ann L. Whitman


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