Arousal frequency in heart failure found to be a unique sleep problem

Findings show that factors other than central sleep apnea may contribute to poor sleep quality in heart-failure patients. A study in the Jan. 1 issue of the journal Sleep demonstrates that the frequent arousals from sleep that occur in heart failure patients with central sleep apnea (CSA) may reflect the presence of another underlying arousal disorder rather than being a defensive mechanism to terminate apneas.
Principal investigator, Douglas Bradley, professor of medicine at the University of Toronto said that researchers involved in the study were surprised that using CPAP to alleviate CSA had no effect on arousals and no effect on sleep structure.
Bradley said, "These results indicate that unlike OSA, arousals from sleep in CSA are not protective, but probably have the opposite effect: they appear to be causative. This finding suggests that future studies should explore preventing arousals from sleep in order to treat CSA."
Results indicate that after three months of treatment with continuous positive airway pressure (CPAP) therapy, heart failure patients with CSA show no significant improvement in the frequency of their arousals or in their sleep structure even though breathing pauses are significantly reduced by 55 percent from 35.4 central apneas and hypopneas per hour to 16.1 events per hour. Arousals remain high (24.3 arousals per hour on CPAP compared to 28.8 at baseline), total sleep time stays the same at 318 minutes, and sleep efficiency remains low at 70 percent.
Data were analyzed from 205 heart failure patients with CSA who were enrolled in the Canadian Continuous Positive Airway Pressure for Patients with Central Sleep Apnea and Heart Failure trial, a prospective, randomized, multicenter clinical trial. Participants were between 18 and 79 years of age, and they were randomly assigned to a CPAP treatment group (97 members) or a control group (108 members). CSA was defined as an apnea-hypopnea index (AHI) of 15 or more with more than 50 percent of apneas and hypopneas central in nature. Members of both groups were assessed by overnight polysomnography at baseline and again after three months. Participants in the treatment group were instructed to use CPAP nightly for six or more hours, and their actual usage time was 4.6 hours per day.
According to the authors, arousals in patients with obstructive sleep apnea (OSA) are considered to be an important defense mechanism to terminate apneas, and treating OSA with CPAP immediately reduces the frequency of arousals. In contrast, arousals in heart failure patients with CSA often occur several breaths after apnea termination.
The authors suggest that hear failure patients with CSA may have a "predisposition to hyperarousability," and in some there may be an underlying arousal disorder accompanied by sleep disruption that is neither a consequence of CSA nor of impaired cardiac function. In heart failure patients with CSA, arousal from sleep may be incidental to, or play a causative role in, the development of CSA by rendering the respiratory control system unstable. Thus factors other than sleep apnea such as pulmonary congestion during the night, other comorbidities, or medications, may explain the frequent arousals that heart failure patients experience.

Women Who Sleep Less Than 8 Hours Live Longer

How much sleep is too much or too little? For women, researchers at the University of California, San Diego say that to live longer, the optimal number is less than 8 hours, and that 5.0 to 6.5 hours is ideal.

Eight hours is too much sleep for women

In the new study, a team of investigators evaluated data originally collected between 1995 and 1999 from 459 women ranging in age from 50 to 81. That study had indicated women who slept 6.5 to 7.5 hours per night had the best survival rates.
Now, 14 years later, the researchers took another look at the original group of women, of whom 444 could be identified for evaluation purposes. Eight-six women had died.
According to the study’s lead scientists, Daniel F. Kripke, MD, professor emeritus of psychiatry at UC San Diego School of Medicine, “when sleep was measured objectively, the best survival was observed among women who slept 5 to 6.5 hours. Women who slept less than five hours a night or more than 6.5 hours were less likely to be alive at the 14-year follow-up.”
The researchers also found that obstructive sleep apnea among older women did not predict an increased risk of death. Kripke noted that while sleep apnea may be associated with a greater risk of death among younger women, “it does not seem to carry a risk in the older age group, particularly for women.”
Countless studies have explored the optimal amount of sleep needed for various populations, from infants to the elderly. According to the National Sleep Foundation, there is no “magic number.” Visitors to the Foundation’s website will find that “not only do different age groups need different amounts of sleep, but sleep needs are also individual.”
That said, research shows that getting too little sleep is associated with many health concerns, including inhibited productivity, difficulty remembering and consolidating information, increased risk for motor vehicle accidents, increase in obesity, increased risk of diabetes and heart problems, and increased risk for psychiatric conditions. Some research also shows that too much sleep (generally considered more than 9 hours or more) is associated with an increased risk of illness and morbidity.
Are people losing sleep over worrying whether they are getting enough or too much sleep? According to Kripke, the results of this new study should provide some answers, at least for women who may worry about sleeping less than 8 hours. “This means that women who sleep as little as five to six-and-a-half hours have nothing to worry about since that amount of sleep is evidently consistent with excellent survival.”