People have long known that sleep deprivation affects the brain but most people see their sleepiness as a necessary sacrifice, so they can find the time to excel at work, take care of family, or enjoy their hobbies and their social life. Now research supported by NIH's National Institute on Aging (NIA) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) reveals that sleeping affects the body as well as the mind.
The new study, conducted at the University of Chicago Medical School, found that after being deprived of sleep, young men's bodies metabolized glucose less effectively — a well-recognized risk factor for the development of insulin resistance, obesity and high blood pressure. The sleep-deprived men also showed higher levels of the stress hormone cortisol — another risk factor for insulin resistance, and for memory problems as well. These conditions mimic some of the hallmarks of aging, and can lead to diabetes and high blood pressure.
The study was performed on healthy young men between the ages of 18 and 27. They spent 16 consecutive nights in a clinical research center — supported by NIH's National Center for Research Resources — where their sleep patterns were carefully controlled. On the first night they spent eight hours in bed; for six nights they spent only four hours in bed; and for the last seven nights they spent 12 hours in bed. The last period of extended nights showed that the effects of sleep deprivation could be corrected. It also showed improvements over the "normal" eight hours, reinforcing previous studies that found eight hours of sleep may not be enough for young adults.
According to the authors, no previous study has assessed the potential health impacts of chronic sleep deprivation on the body. Although this is a small study and limited in many respects, it does raise serious questions about the tendency to dismiss lack of sleep as merely an inconvenience. — The Lancet, 354:1435-1439
NIA can be reached at 301-496-1752 or at http://www.nih.gov/nia/> on the Internet. For information on diabetes, call NIDDK's Diabetes Information Clearinghouse at 301-654-3327 or log on to http://www.niddk.nih.gov/ on the Internet.
For general information about sleep, call 301-496-5751 or visit "Brain Basics: Understanding Sleep" from the National Institute of Neurological Disorders and Stroke (NINDS) at <http://www.ninds.nih.gov/health_and_medical/pubs/understanding_sleep_brain_basic_.htm> on the Internet.
For information on sleep disorders, visit the National Center on Sleep Disorders Research (NCSDR) of the National Heart, Lung, and Blood Institute (NHLBI) at <http://www.nhlbi.nih.gov/about/ncsdron> the Internet. — a report from The NIH Word on Health, June 2000.
New Screening Tool for Cervical Cancer
Testing for the presence of human papillomavirus (HPV) may be a useful new screening tool for cervical cancer. The authors of a recently published study funded by NIH's National Cancer Institute (NCI) concluded that "[HPV] testing should be considered as a viable cervical cancer screening method that has come of age technically.
Cervical cancer is one of the leading cancers in women worldwide. According to NCI, most of these cancers could be prevented or found at an early, curable stage with regular screening. Currently, the Papanicolaou (Pap) test, which uses a microscope to detect changes in cells taken from the cervix, is used for regular screening. But scientists suspected that there might be an easier, and perhaps even a more effective way to screen for cervical cancer risk.
Nearly all cervical cancers show evidence of HPV infection. More than 70 types of HPV have been identified; 30 types infect the cervix, and about 15 types are associated with cervical cancer. With this in mind, the researchers decided to see whether testing for these latter types of HPV would be an effective screening method.
A randomly selected group of 8,554 women from Guanacaste Province, Costa Rica, where cervical cancer rates are high, were tested for the presence of DNA from the cancer-causing HPV types. At its best, HPV testing detected 88.4 percent of the "precancerous lesions" which precede cervical cancer, and all 12 of the cancers in the group. Women without cancer or precancerous lesions correctly tested negative 89 percent of the time. For comparison, the Pap smear detected 77.7 percent of the precancerous lesions and correctly tested negative 94.2 percent of the time. HPV testing, then, can detect more precancerous lesions than the Pap smear test, but it also gives more false positives.
False positives can lead to costly follow-ups tests, so research on how to reduce false positives while maintaining the sensitivity of HPV testing continues. However, the new screening method shows potential to reach women who otherwise might not undergo screening at all — for example, women living in underdeveloped areas where conventional Pap testing is not available. Exactly how HPV testing will eventually be used is hard to foresee right now, but this study gives hope that doctors will soon have more flexibility in screening for cervical cancer. — JAMA 283,1:87-93
For more information about cervical cancer, call NCI's Cancer Information Service (CIS) toll free at 1-800-4-CANCER (1-800-422-6237) or visit http://cancernet.nci.nih.gov/wyntk_pubs/cervix.htm on the Internet. — a report from The NIH Word on Health, June 2000.
Growing New Brain Cells
Not long ago, scientists believed that people couldn't make new brain cells once they reached adulthood. Recently they came to realize that new nerve cells are produced in the brain, and that they may play a role in learning and memory as we age. Now, for the first time, immature cells have been isolated from the adult human brain, grown in the laboratory, and shown to develop into nerve cells. This accomplishment, partially supported by NIH's National Institute of Neurological Disorders and Stroke (NINDS), is a significant step toward developing therapies to replace brain cells lost or damaged in Parkinson's Disease and other brain disorders such as stroke.
A region from the hippocampus, a part of the brain involved in learning and memory, was dissected free from brain samples that were taken from eight adult male patients in the course of their medical treatments. The researchers, from both Japan and the United States, were able to isolate immature cells called neuronal progenitor cells from the region. They showed that these cells were able to divide on culture plates in the laboratory. The cells could then develop to the point where they could produce an electrical signal akin to that seen in developed brain nerve cells.
New brain cell production has been tied to learning in mice, and scientists think that the same may be true for people. Neuronal progenitor cells might eventually be used to treat degenerative brain disorders by reintroducing cells grown in the laboratory back into the brain. Already, fetal cell therapy has shown some potential in people with Parkinson's disease. The technical hurdles to using these neuronal progenitor cells for such therapy remain formidable, and are doubtless a long way off. Nevertheless, getting neuronal progenitor cells to divide and develop into nerve cells in the laboratory is an important step toward this goal. — Nature Medicine 6,3:271-277
For information about Parkinson's disease, visit <http://www.ninds.nih.gov/health_and_medical/disorders/parkinsons_disease.htm> on the Internet. For more information about the fetal cell therapy in Parkinson's patients mentioned in this capsule, visit <http://www.ninds.nih.gov/news_and_events/freedfinal.htm?type=archived> on the Internet. — a report from The NIH Word on Health, June 2000.
For more information on Research Capsules, contact: Harrison Wein, Ph.D. Writer and Editor NIH Office of Communications and Public Liaison Phone: 301-435-7489 Fax: 301-402-1485 E-Mail: weinh@od.nih.gov
