Please Explain from WNYC New York Public Radio

Dr. Matthew Ebben of Weill Cornell Medical College's Center for Sleep Medicine discusses what normal sleep is and what happens when it gets disrupted by disorders such as insomnia, snoring, sleep apnea, restless leg syndrome, sleep walking, and narcolepsy. He explains the causes and treatments for sleep problems. Dr. Ebben is Assistant Professor of Psychology in Clinical Neurology at Weill Cornell Medical College.

More than 40 million Americans have arthritis, and it's the leading cause of disability for people who are 65 and older. Almost everyone over 70 has some form of arthritis, but it can affect much younger people too. Dr. Clark Smith, an Assistant Clinical Professor of Rehabilitation and Regenerative Medicine at?Columbia?University Medical Center, explains what causes arthritis and how to treat it.

Medical marijuana is legal in 20 states, and is used to treat symptoms of multiple sclerosis, AIDS, side effects of chemotherapy, as well as pain, glaucoma, epilepsy, insomnia, and anxiety. Dr. Igor Grant, Distinguished Professor and Executive Vice-Chair of the Department of Psychiatry at UCSD School of Medicine and Director of the UC Center for Medicinal Cannabis Research, tells us about his research into the possible utility of cannabis compounds in the amelioration of certain severe manifestations of disease. And Jim Rendon, author of Supercharged: How Outlaws, Hippies, and Scientists Reinvented Marijuana, talks about the changing attitudes toward marijuana and how the increasing acceptance of medical marijuana is changing the legal and commercial landscape.

During the last ice age, glaciers covered the entire northern part of our continent, shaping mountains and carving valleys. Today, most of the earth's glaciers are found in Antarctica and Greenland, but there are glaciers on every continent, including Africa, most commonly above the snow line. Tim Creyts, a glaciologist with the Lamont-Doherty Earth Observatory, Earth Institute, Columbia University, explains what glaciers are, how they move and sculpt the landscape, and how climate change is affecting glaciers around the world.

Get up, stand up! Evidence is mounting that sitting for long stretches of time — in a car, at a desk, or on the couch — is bad for our health. A sedentary way of life and spending hours sitting down seems to increase the risk of death from cardiovascular disease and cancer. Dr. James Levine, professor of medicine at the Mayo Clinic, professor at Arizona State University, and a national leader in obesity research, and Dr. Wayne Stokes, director of Sports Medicine Rehab at NYU Langone Medical Center, explain how sitting causes health problems and what we can do to counteract them.Research by Dr. Levine and others reveals that ?sitting for more than 2 hours a day is directly linked to health problems like obesity, metabolic disorders, increased blood pressure, high blood sugar, excess body fat around the waist and high cholesterol. One Australian study showed that adults who watch an average of six hours of television day over their lifetimes will die 4.8 years sooner that adults who don't sit for hours watching television. ?"It's rather like having a Ferrari idling for three months. It gets clogged up with grit and oil and sludge, and that kind of sludge is what you're seeing in the muscle bands," Levine said. He also said that moving around improves intuitive and creative thinking. "There's cognitive dulling and we're just not as smart as we could be" when we sit all day.Even regular exercise at the gym isn't enough to counteract the negative effects of sitting at our desks and in front of the television for long stretches. We have to move more and more often. Levine and Stokes recommend using standing desks, even a treadmill desk, or, at the very least, standing or moving every 15 minutes or so while you're sitting at work — get up to talk on the phone, go talk to colleagues instead of e-mailing them, take short walks and standing breaks. In addition to the metabolic problems caused by inactivity, Stokes points out that sitting leads to slouching and poor posture can cause back and shoulder pain that many people who sit in front of a computer all day experience.But don't worry if you've been too sedentary — it's never too late to make changes. "If one embarks on a program of chairlessness, of getting out of the chair and starting to move more," Levine said, "one can achieve very, very significant improvement."

On this week's Please Explain. Dr. Philip Muskin, MD is the Chief of Consultation-Liaison for Psychiatry at the Columbia University Medical Center of the New York Presbyterian Hospital and Professor of Psychiatry, described how hypnosis works and whether it can be?used it to change or control behavior.We may think of being hypnotized as zoning out, but in fact, Dr. Muskin says, we're "in a very focused state of concentration." That's because "in hypnosis, you focus yourself to do one thing.""Hypnosis is not an abnormal state. It is a completely normal state. We are in trances - every single one of us - every single day." If you've ever found yourself daydreaming in a boring lecture or a long meeting, you've put yourself in a kind of trance.Soldiers in the middle of a firefight can naturally go into a trance to protect themselves and feel less pain.People vary in their ability to be hypnotized. It's a bell curve with most of us be in the middle. And, Dr. Muskin notes, "many athletes are much more hypnotizable than they realize."Dr. Muskin said that transcendental meditation and other similar kinds of meditation and activities are trance states. "You're pulling your awareness in, you're disconnecting...you're doing this one thing with all of your mental ability." And there are all sorts of physiologic changes that come along with those states that make us feel pretty good.

We'll find out how hypnosis works and why on this week's Please Explain. Dr. Philip Muskin, MD is the Chief of Consultation-Liaison for Psychiatry at the Columbia University Medical Center of the New York Presbyterian Hospital and Professor of Psychiatry, looks at what hypnosis is used for and if it's possible to use it to change or control behavior.

A recent long-term study questioning the benefits of annual mammograms for older women. This week's Please Explain is about breast cancer. Dr. Larry Norton, Deputy Physician-in-Chief for Breast Cancer Programs at Memorial Sloan Kettering Cancer Center, describes how the disease is detected and the ways it can be treated. Cancer cells not only divide more than normal cells, they can move around the body and "set up shop in other places" in the body. However, people die from tumors, which are made up of cancer cells and other cells."Any lump should be tested," Dr. Norton says, and he recommends a core biopsy because it enables doctors to see the relationship between cancer cells and other cells.According to Dr. Norton, the study that recently made headlines by questioning the benefits of annual mammograms is "actually a very old study that's been reported before." And because the technology has improved dramatically in the last few decades, "the mammograms [administered in the study] were just not mammograms by modern standards." The overwhelming evidence, he says, supports the use of mammography.Dr. Norton says that women should be getting annual mammograms starting at age 40. "With breast cancer, if you find it early, it makes a big difference in the management." However, mammograms aren't necessarily that effective for younger women, and for certain women, particularly those with what are called "thick breasts," an MRI may be an important diagnostic tool.Certain things predispose people to breast cancer including hormone replacement therapy; radiation exposure, but it has to be significant; and obesity.The key to better understanding breast cancer, Dr. Norton says, is more research on breast cancer causation. And that requires more funding. "This is probably one of the most exciting times in all of biomedical history in terms of making advances."

A recent long-term study questioning the benefits of annual mammograms for older women. This week's Please Explain is about breast cancer. Dr. Larry Norton, Deputy Physician-in-Chief for Breast Cancer Programs at Memorial Sloan Kettering Cancer Center, describes how the disease is detected and the ways it can be treated.

This week's Please Explain is all about genius. Dean Keith Simonton, professor of psychology at the University of California, Davis, talks about what exceptional intelligence is and how it can influence creativity, leadership and achievement. And we'll find out how genius and intelligence are measured.

This week's Please Explain is all about dogs. We'll find out the evolutionary roots of domestic dogs, what it means when your dog wags its tail, and why some breeds are easier to train than others. Veterinarian Dr. John Ciribassi, who was one of the editors of Decoding Your Dog, and pet expert and journalist Steve Dale, who contributed to the book, take your calls and questions about man's best friend.

We'll find out how apps are created and get recommendations for must-have apps--tools that can help find parking, find a ride, track calories, and more. Bruce Upbin, managing editor of Forbes, and Geoffrey Fowler, tech columnist for the Wall Street Journal, join us.

We'll find out how apps are created and get recommendations for must-have apps--tools that can help find parking, find a ride, track calories, and more. Bruce Upbin, managing editor of Forbes, and Geoffrey Fowler, tech columnist for the Wall Street Journal, join us.?Let us know what apps you can't live without! Leave a comment, below.

Maxwell Ryan, CEO and founder of Apartment Therapy, gives advice and answers questions about how to get organized for the new year. From cleaning out closets and clearing clutter, from financial files to the tangle of wires behind your television and stereo.

On this week's?Please Explain, Marion Nestle, author of?Eat, Drink Vote: An Illustrated Guide to Food Politics;?Food Politics: How the Food Industry Influences Nutrition and Health;?What to Eat, among other books, talks about the politics of food.