Caption: Colorized 3D reconstruction of dendrites. Neurons receive input from other neurons through synapses, most of which are located along the dendrites on tiny projections called spines. Credit: The Center for Sleep and Consciousness, University of Wisconsin-Madison School of Medicine
People spend about a third of their lives asleep. When we get too little shut-eye, it takes a toll on attention, learning and memory, not to mention our physical health. Virtually all animals with complex brains seem to have this same need for sleep. But exactly what is it about sleep that’s so essential?
Two NIH-funded studies in mice now offer a possible answer. The two research teams used entirely different approaches to reach the same conclusion: the brain’s neural connections grow stronger during waking hours, but scale back during snooze time. This sleep-related phenomenon apparently keeps neural circuits from overloading, ensuring that mice (and, quite likely humans) awaken with brains that are refreshed and ready to tackle new challenges.
This past weekend, I attended a scientific meeting in New York. As often seems to happen to me in a hotel, I tossed and turned and woke up feeling not very rested. The second night I did a bit better. Why is this? Using advanced neuroimaging techniques to study volunteers in a sleep lab, NIH-funded researchers have come up with a biological explanation for this phenomenon, known as “the first-night effect.”
As it turns out, the first night when a person goes to sleep in a new place, a portion of the left hemisphere of his or her brain remains unusually active, apparently to stay alert for any signs of danger. The new findings not only provide important insights into the function of the human brain, they also suggest methods to prevent the first-night effect and thereby help travelers like me in our ongoing quest to get a good night’s sleep.
Credit: Karen Laubenstein (Big Game Alaska)/U.S. Fish and Wildlife Service
When bears, bats, and other animals prepare to hibernate, they pack on fat at an impressive pace to almost double their weight. As they drift off into their winter slumber, their heart rates, breathing, and metabolism slow dramatically. Hibernating mammals can survive in this state of torpor for a period of weeks or even months without eating or drinking anything at all!
It’s a fascinating and still rather mysterious process—and one that William Israelsen of The University of Texas Southwestern Medical Center, Dallas, thinks may yield intriguing insights with implications for human health. A recipient of a 2015 NIH Director’s Early Independence Award, Israelsen plans to use a little-known mouse species to study hibernation in the laboratory at a level of detail that’s not possible in the wild. He especially wants to learn how hibernating animals shift their metabolic gears over the course of the year, and what those findings might reveal about human obesity, cancer, and other health conditions.
Ketema Paul remembers being wowed at an early age by his cousin’s chemistry set and always feeling drawn to science. This interest followed him to Howard University, Washington, D.C., where he earned an undergraduate degree in biology, and on to Georgia State University, Atlanta for his Ph.D. Now, an associate professor at Atlanta’s Morehouse School of Medicine and the subject of our latest LabTV video, Paul runs his own neuroscience lab studying sleep disorders, which affect at least 60 million Americans as chronic or occasional problems and account for an estimated $16 billion in medical costs each year .
Paul’s path to the research bench is an interesting one. The product of a tough neighborhood in Washington, D. C., Paul lost a lot of friends to violence and faced many uncertainties. After college, he moved to Atlanta to try his hand at being a music producer and eventually took a side gig as a disc jockey for the campus radio station at Georgia State. Then one day after his radio show, Paul wandered over to have a look inside a nearby neuroscience lab just for kicks and opened the door on a discussion that would change his life.
Have trouble sleeping? If so, you’re not alone. At least 40 million Americans suffer from chronic, long-term sleep disorders, and another 20 million have occasional problems. Many more (including me) just don’t seem to find enough hours in the day and night to get adequate sleep.
Lack of sleep has been linked to a variety of health conditions, including diabetes, cardiovascular disease, obesity, and depression. Sleep deprivation can also affect alertness and reflexes. And that can be lethal—tired drivers cause an estimated 100,000 motor vehicle accidents and 1,500 vehicle-related deaths each year.
So, how much sleep do you really need? While there’s a lot of individual variation based on age, health status, and genetic factors, average daily sleep needs are:
16 to 18 hours
11 to 12 hours
9 to 10 hours
7 to 8 hours
And a special note for expectant parents: women often need several extra hours of sleep during the first three months of pregnancy.
If you’d like to test your sleep I.Q., check out this online quiz.