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Counting Sleep

Illustrations by Dung Hoang

Counting Sleep (continued)

These differences in transitions overlooked by traditional measures,” says Caffo, “may produce new clinical indices for measuring sleep disturbance.

Subjects with sleep-disordered breathing had a greater number and higher rates of sleepstage transitions than those without sleepdisordered breathing, the authors note. All these transitions are chopping up the duration spent in each sleep stage. Overall, they may get the same amount of REM sleep, but the REM sleep is composed of more, shorter episodes. Researchers believe people who experience rapid transitions may get the same number of minutes of REM sleep but it may not be the same quality.

“This new way of looking at the data essentially gives you a more complete picture,” says Caffo, “and a better predictor of disease."

Bad sleep is clearly linked with poor health, but researchers now want to know if they can prevent cognitive and functional decline by treating sleep problems.

Crainiceanu, PhD, agrees. “You can see things that were impossible to think about before,” he says, such as differences in EEG data for smokers versus non-smokers or among different age groups. He describes the advances from the biostatistical viewpoint in terms of multi-resolution analytical tools: “This allows researchers to investigate multiple sub-groups while quantifying differences all the way from the fine detail of an individual’s raw EEG data (125 observations per second) to the heavily summarized individual’s sleep architecture.”

At the population level, these analytical methods are now allowing researchers to examine data from previous cohort studies in much greater detail than before.

This comes at a time when there is finally a rich trove of sleep data to be explored.

After nearly two decades, several longterm studies have amassed the nocturnal patterns of thousands of people. One, the Osteoporotic Fractures in Men Study, known as MrOS or more informally “Mister Os,” began in 2000 with 5,995 men ages 65 and older and continued until this year. Another, with 9,700 women in the same age range, began in 1986 in Minneapolis, Portland, Oregon and Pittsburgh and continued over 20 years. And the Sleep Heart Health study coordinated by Johns Hopkins recruited more than 6,400 people in cities across the U.S.

With the greater computational capacity gained in the last two decades, researchers can now perform more fine-grained analysis of that EEG data and can ask, Do any disturbances during segments of a person’s sleep correlate with their medical conditions? Answering that question with quantitative input “is extremely vital for moving this field forward,” says Punjabi. For him, the PLoS Medicine paper linking sleep disruption to mortality is more a prelude than a finale.

“Instead of saying, ‘The story is done here,’” he observes, “I think the story is just starting.” He calls for intervention studies that explore whether reversing or minimizing the physiological effects of sleep apnea and other sleep disorders can decrease the risk of mortality.

The Case for Treatment

Adam Spira, an assistant professor in Mental Health, sees opportunities for improving treatment for sleep disorders in psychology and medicine. Research fascinates him, and what really interests him is not simply the evidence that bad sleep may be linked to health problems, but the potential to ameliorate those problems if there is indeed a causal link. 

"We have good treatments for bad sleep in older adults, whether it’s insomnia or apnea,” he says. Behavior therapy and cognitive-behavioral therapy (CBT), for instance, is effective in reducing insomnia, and CPAP therapy is useful for addressing apnea. “So,” he says, “it will be really good to know if treating these problems can improve those outcomes.” If so, some problems typically accepted as a product of aging may be treatable.

Spira, PhD, came to Hopkins in 2008 after a fellowship in geriatrics and geropsychiatry at the University of California-San Francisco (UCSF), where he looked at the sleep of older people in epidemiological terms. He received an invitation to come to Hopkins while he was working on studies of sleep in MrOS and the Study of Osteoporotic Fractures (SOF) with Katie Stone, a scientist at the California Pacific Medical Center Research Institute. Spira respects the team of Hopkins scientists working on sleep research, and was drawn by the impressive range of interdisciplinary collaborators. “You’ve got a biostatistician, you’ve got Naresh who is a pulmonologist and critical-care medicine doc, you’ve got a professor in epidemiology here, and then my PhD is in clinical psychology.”

With a major grant from the National Institute on Aging recently approved, Spira and colleagues at the Bloomberg School and the School of Medicine aim to delve further into the rich material of the Mister Os and SOF studies and detect links between poor sleep and functional decline. The five-year career development award will allow Spira to learn from mentors including Punjabi, Bloomberg School Mental Health Professor George Rebok, PhD, and his postdoc mentor Kristine Yaffe, MD, Psychiatry and Epidemiology professor at UCSF. The study will explore that data in more detail for connections between sleep disturbance and decline in performing daily functions such as housework and grocery shopping.

Punjabi sees that work as critical. “What’s really necessary—and this is what Adam’s starting to work on with the Mister Os study,” he says, “is objective, fine-grained monitoring of actigraphy, which is a nice way to look at sleep duration objectively.”

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  • kay smolin

    palo alto 94303 11/20/2009 09:22:54 PM

    good info, need more specific fix

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