February 16, 2005
What was once considered a mere aggravation is now being linked to serious health risks as scientists chart our tenuous relationship with that most precious of commodities -- a good night's sleep.
For many people, sleep is a fickle friend. As teenagers, it was there for them, a dependable companion who offered retreat from the stresses of waking adolescent life.
But for many, sleep can get become less dependable as the years go by or, perhaps, it was never reliable to begin with.
If your single certainty about sleep is that the only time you are guaranteed to be sleepy is after the alarm goes off, then you are not alone. According to polls conducted annually by the National Sleep Foundation, about two-thirds of American adults and children experience frequent sleep problems.
That includes all the people who go to bed worried about their inability to fall asleep - a worry that prevents them from falling asleep - and those who wake in the small hours of the morning and can't coax sleep's return.
It includes the millions who have sleep apnea, many without knowing it, whose breathing is strained at night and who either wake frequently or sleep long hours but rarely feel rested. And it includes those few who thrash around in bed, sleepwalk or wake up screaming.
And, bleary eyed, they struggle out of bed each morning to face the unrelenting pace of modern life but, until recently, who knew that there was a larger price to pay for all that lost sleep?
Modern sleep research began about 50 years ago, but it's only been in the last decade or so that the medical community has started paying attention, thanks to studies showing a significant relationship between the quantity and quality of sleep and many health problems. Insufficient sleep affects the secretion of hormones that are linked to obesity, for example.
Obesity, in turn, is strongly linked to sleep apnea in adults, in which the airway is obstructed during sleep, inhibiting air flow and causing frequent awakening during the night. Interrupted sleep is associated with hypertension and cardiovascular problems. Insufficient sleep also impairs the body's ability to use insulin, which can contribute to the onset of diabetes.
"What got me interested in sleep medicine were studies showing an association between sleep apnea in children and poor school performance, behavior problems and attention deficit and hyperactivity disorder as well as cardiovascular problems," says Narong Simakajornboon.
He's an associate professor of pediatric pulmonology whose area of interest is the control of breathing. He's also the medical director of Tulane's Comprehensive Sleep Medicine Center, which was founded by former Tulane professor David Gozal in 1997. The focus of the center was initially the sleep problems of children, particularly as they related to sleep apnea. Simakajornboon and Gozal share a research interest in how sleep apnea can lead to behavioral problems.
"Sometimes people regard sleep as a waste of time," says Beth Wee. "But clearly we need it."
Wee is the lab supervisor in the Department of Cell and Molecular Biology whose field of research has been circadian rhythms. She points out that while all animals sleep, the amount of sleep varies widely among species. Those at the top of the food chain, who eat protein-rich diets and have few if any predators, sleep long hours. Cats sleep around 15 hours a day; cows, sheep and horses sleep less than four hours daily.
We humans spend about a third of our life asleep -- at least if we're lucky -- yet much about sleep is still poorly understood. What is well-established is that there are distinct stages of sleep in which different parts of the brain are active. There are two basic kinds of sleep, slow-wave sleep and REM sleep. Slow-wave sleep, which itself has four phases, is characterized by slow, regular brain waves as captured by an electroencephalogram.
REM (for rapid eye movement) sleep is characterized by increased, irregular brain activity. It's also called paradoxical sleep because it seems to be the deepest phase of sleep, yet it is the phase in which the brain is most active. Most dreaming seems to occur during REM sleep, which arrives after the four stages of slow- wave sleep.
One of the theories about why we sleep is that we are ill-equipped to do much of anything else in the pitch black of a moonless night. Of course, sleep seems to serve several functions. The body repairs itself during sleep and REM sleep seems to be necessary for your brain to process information and consolidate it in long-term memory.
"Sleep is definitely involved in learning and memory," says Wee. "If you learn new information and then 10 hours pass in which you get some sleep, you'll remember the information better than if the same amount of time passed without sleep. I tell my students, "you need to study, but make sure you sleep.'"
However, every person's cycle and need for sleep are highly individual. While the rule of thumb is that we need between seven and eight hours of sleep a night, there are those who feel well-rested with much less, and others who seem to need a bit more. And your cycle changes over a lifetime. Newborn babies sleep in two-hour increments with short intervals of wakefulness. The amount of time spent asleep gradually increases and peaks in adolescence. As you get older the trend reverses, with shorter but more frequent bouts of sleeping. The difference is that babies spend a lot of time in REM sleep, but in older people the amount of REM decreases.
Studies suggest that about 30 percent of kids with attention deficit and hyperactivity disorder also have sleep disorders, which may be a cause of their hyperactivity. According to a 2004 poll by the National Sleep Foundation, American children seem to be getting less sleep than experts recommend.
And the lack of sleep can put kids at risk for injuries and school problems. Up till the age of 12, kids need nine hours of sleep a night. Parents might not realize that sleep is a problem when a child seems full of energy -- but that can actually be the result of not getting enough sleep.
Simakajornboon has done sleep studies with children who have restless leg syndrome and periodic movement disorder, and found that iron supplementation can help. He has a project looking at sleep problems in children with cystic fibrosis, a disease that affects the lungs and makes it hard to breathe and, not surprisingly, often makes it hard to sleep. Researchers found that if you improve patients' sleep, you often improve their ability to cope with the disease. Simakajornboon believes that doctors should routinely pay attention to the sleep patterns of patients with cystic fibrosis and other diseases.
Currently, his main research interest is the effect of prenatal nicotine exposure on babies. Sudden infant death syndrome, which occurs when babies are asleep in bed, is associated with in utero nicotine exposure. "We see that nicotine has a great impact on breathing patterns in newborns," he says. "When we look at nicotine-exposed rat pups, we find they are not able to cope that well with low oxygen levels, sometimes to the point that cell death in certain areas of the brain occurs."
Simakajornboon is looking at the rat model to see how nicotine exposure alters neurotransmitters. He's also doing clinical sleep studies with young children of mothers who smoked while pregnant. Women who smoke may try to quit when they get pregnant by using a nicotine patch or gum, but unfortunately Simakajornboon's studies suggest that nicotine in any form adversely affects the baby's respiratory control.
Tulane's is the only pediatric sleep center in Louisiana, but as it has grown, it has expanded its focus. Houman Dahi is the new director of adult sleep research at the center, which now sees as many adults as children. He's joined by Supat Thammasitboon, another new member of the sleep center's faculty.
Dahi's newest research project is looking at sleep and sleep deprivation in patients in hospital intensive-care units. About 85 percent of patients suffer from delirium while in the intensive-care unit. They usually don't sleep well, either. Dahi suspects that the delirium may be linked to sleep deprivation. Patients complain most about the noise preventing them from sleeping, but the fact is that the lights remain on 24 hours a day and patients are continually monitored while regularly being asked questions and given treatments. Dahi will soon begin doing sleep studies with patients in the intensive-care units at Tulane Hospital.
He and Thammasitboon also are helping build a partnership with the sleep center at the Veterans Administration Hospital, which is run by Jeff Nicholl, assistant professor of psychiatry and neurology.
Right now there are only two beds at the VA's center and a waiting list to get in. But the VA will soon expand to four beds with upgraded equipment, which will offer Tulane researchers more opportunities to do sleep research with a distinct group of adult subjects.
The VA clinic also will be part of Tulane's fellowship program in sleep medicine, which is one of only about 30 in the nation. Tulane's sleep center trains two fellows a year, one focusing in pediatric sleep medicine and the other in adults.
Sleep medicine is a growing, interdisciplinary field, and Simakajornboon wants to assist the field to grow internationally. To that end, he helped begin another fellowship program in which physicians from other countries come to Tulane to do sleep research.
The growth of the field also is affecting sleep technicians, who setup and monitor the sleep studies. They're in short supply and are finding themselves in demand. Lisa Murry, the sleep center's chief technician, was recently recruited to Tulane, drawn by the opportunity to work on clinical research. In addition, she's helping to develop sleep curriculum for students from the Louisiana State University School of Allied Health's respiratory therapy program, who will do a rotation at the sleep center in the near future.
Last year, more than 700 overnight studies were performed at the center. Subjects may have to be monitored two nights in a row, because it takes a night to get acclimated.
"But you'd be surprised how well people can sleep in the lab," Simakajornboon says. [For another opinion see the accompanying sidebar.]
The sleep lab is state-of-the-art, with the ability to monitor up to 50 channels on a subject, to capture everything from brain waves to eye movement, leg-twitching to snoring.
The lab is useful to diagnose, study and treat rare sleep disorders such as narcolepsy, a condition that causes people to suddenly fall asleep at unexpected times. But doctors at the sleep center also see a lot of garden-variety problems that lead to sleep deprivation. The loss of sleep is simply one of the hazards of contemporary life, says Simakajornboon. "The light bulb drastically changed human life. Now you can work at night and sleep in the daytime."
When people work at nighty -- when the body naturally wants to sleep -- alertness and performance are impaired and accident rates go up.
The best way to deal with the common sleep problems that are induced or exacerbated by modern lifestyles is to reinforce the link between your individual cycle and the daily cycle of light and dark. Expose yourself to light in the morning, don't sit in front of the computer late at night. Exercise is good, but exercise close to bed time might make it hard to sleep.
If you're going to do shift work, it's probably better to stay on the late shift for a relatively long period of time, rather than switching shifts every few weeks. Melatonin, a natural hormone, can be effective in short-circuiting jet lag, but don't take it without consulting your doctor.
Any insomnia that occurs regularly should be addressed. But doctors have become reluctant to treat insomnia with sleeping pills because of the much-publicized threat of addiction and abuse. Yet Simakajornboon believes that medication can play an important role in treating psycho-physiological insomnia -- the kind where you start to associate your own bedroom with the inability to fall asleep.
"Sleeping pills can prevent insomnia from becoming chronic. There's a new generation of drugs that are shorter-acting, nonaddictive and don't suppress respiration," says Simakajornboon. But he stresses that doctors shouldn't prescribe sleeping pills unless they understand what's the underlying cause of the insomnia.
"People think sleep is a luxury but it's very important."
Heather Heilman is an editor in Tulane's Office of University Publications.
Tulane University, New Orleans, LA 70118 504-865-5000 firstname.lastname@example.org