At the end of January, the last participant nationwide was enrolled in
the Sleep Heart Health Study (SHHS). Even before that person's sleep study was
processed, however, study investigators had been analyzing the data and making
interesting observations. As you know, the ultimate goal of the SHHS is to determine
whether sleep apnea is a risk factor for hypertension, heart disease and stroke. It
is not possible to answer these questions yet, but analyses to date confirm that sleep
apnea does appear to be associated with hypertension.
In a paper presented at the American Heart Association in Santa Fe, New Mexico
recently, a SHHS investigator from Johns Hopkins University, Dr. F. Javier Nieto
presented data showing a relationship between hypertension and sleep apnea. In this
analysis, those with severe sleep apnea were more likely to have hypertension than those
with less severe sleep apnea. This association was present after correction for other
factors such as body weight and age, which also are risk factors for hypertension. In
addition, the relationship was particularly strong in those under 60 years of age.
Although this data is not conclusive, it does suggest that sleep apnea may have a role
in the development of hypertension.
The SHHS has performed preliminary analyses pertaining to risk factors for sleep apnea.
At the American Thoracic Society Meeting in San Francisco last year, study investigators
showed that sleep apnea occurred more often in men than in women, and that increasing
amounts of apnea was associated with increased sleepiness.
In addition to these preliminary analyses, SHHS has addressed several technical issues.
First, by performing over 6,300 sleep studies nationwide, the study has documented the
feasibility of performing high quality sleep studies at home with a high success rate
(greater than 90%). Second, by performing repeat studies in a small number of SHHS
participants, SHHS has demonstrated that the results generally do not vary from night to
night. Thus, a single night of study usually is representative of an individual's sleep
and breathing.
Analyses are ongoing in the SHHS and promise to yield new and exciting data pertaining
to sleep and your health. We will keep you informed of these advances in future newsletters.
Thank you again for your participation in this important study.
What is the Annual Survey
The Annual Survey included with this newsletter is one of the most important parts of
our Sleep Heart Health Study. As you know, the primary objective of the study is to find
out if people with a higher number of pauses in their breathing during sleep also have
higher risk factors for cardiovascular disease, such as high blood pressure, heart attack,
and stroke. By completing and returning this survey, you will help us to follow the degree
of cardiovascular risk for people with varying degrees of apnea. Won't you please take a
few minutes now to complete the questionnaire and mail it back in the postage paid envelope?
Thank You!
The Cognitive Substudy
The cognitive substudy is currently underway. One primary goal of this substudy is to
investigate how sleep is related to daytime functioning. For example, researchers are
interested in investigating how sleep and sleep disturbance may be associated with
attention, concentration and other mental abilities, and how one feels during the day.
This cognitive substudy will examine various aspects of cognitive functioning, including:
general intelligence (IQ), attention, language, problem solving and perceptual motor skills,
and perception of well-being. We would like to see how these may be related to sleep.
The cognitive substudy is a one time event, which will take approximately 2 1/2 to 3
hours. It can be done either at your home or in our research office arranged at a time that
is convenient for you. Participants in this substudy will receive a summary of their
personal test results and monetary compensation. Participants for this substudy are
selected based on a variety of factors: sex, age, and apnea index (as reported on your
personal sleep summary) to name a few. A total of 100 participants will be enrolled.
Please consider participating in the cognitive substudy if called. Thanks.
Our Tucson site completed the last of our home sleep studies in November 1997. We did a
total of 909 home studies; achieving all demographic recruiting goals. We studied 56%
females and 44% males, including 15% Hispanic, and about 6% African American, Native
American, Asian American, and others. A total of approximately 6300 studies were performed
nationwide, reflecting a representative demographic cross-section of the American population.
The Tucson site participated or is still participating in several substudies:
1. The Night to Night Variability study (N2N): We completed two separate sleep studies
on a variety of participants within a certain time frame. This was to determine if we would
find similar results on different nights of sleep using the same equipment and procedures.
It is important to show that results would not vary greatly from one night to the next
when collecting sleep data.
2. The Urinary Catecholamine substudy: We collected 24 hour urine samples on Sleep
Study Update (con't)
participants which were separated into "day" and "night" samples.
These samples are being analyzed to determine differences in the amount of adrenaline
produced by the body during both awake and sleeping hours. We hope to see differences in
the amount of adrenaline produced by the body based on the number of breathing pauses
(and other factors) during sleep.
3. The Lab vs. Home substudy: We have asked volunteers to undergo two separate sleep
studies; one in their home, and one in the Sleep Lab at UMC. We are hoping to see if there
are differences in sleep data based on where the study takes place (using an identical
hookup). This will help researchers and personal physicians determine the feasibility of
performing diagnostic sleep studies in the home.
4. The Cognitive substudy: (currently ongoing): A study of how sleep disturbances may
affect daytime functioning. (Please read accompanying article).
As you can see, we have made great strides over the past several years. We are learning
very valuable information about sleep and its effects on health. We also realize with a
sincere sense of appreciation that this research has been done only with the help of
participants like you, sacrificing your time and effort for this important purpose.
Thank-you!!!
