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Who wouldn’t enjoy an extra hour or two of sleep before climbing out of bed and getting ready for work? A good night’s rest, or lack thereof, not only contributes to the following day’s productivity levels and emotions, but also its long-term effects are linked to cognitive and cardiovascular health. According to the National Institutes of Health (NIH), one third of Americans get less than seven hours of sleep each night, and research points sleeping less than seven to eight hours each night to health risks such as stroke, obesity, cancer, and high blood pressure.
For National Sleep Awareness Week (April 23 – 29), we asked sleep expert Clifford B. Saper, M.D., Ph.D., to discuss the importance of sleep hygiene, sleep disorders, and current research at Harvard Medical School’s Division of Sleep Medicine, where he conducts his lab research and heads the neurology department. Saper is also a Dana Alliance for Brain Initiatives member and past Dana Foundation grantee.
Between nightmares, bruxism (or teeth-grinding), sleep walking, restless leg syndrome, and insomnia, it seems like most people experience at least one of these conditions at some point in their lifetime. Why is it that so many seem to struggle with something as fundamental and necessary as sleep? What kind of external factors may contribute to these sleep disorders?
Each is a very different problem. Sleep walking, bed-wetting, and night terrors (bad nightmares that awaken children from sleep) are all parasomnias (meaning extra movements during sleep) that have childhood onset and which occur in the deepest stages of slow-wave sleep. Children almost always outgrow these, and treatments usually reduce deep slow-wave sleep (e.g., antidepressants).
Bruxism, restless legs, and periodic leg movements are all movement disorders of adulthood. There are various treatments based on stopping the involuntary or uncontrollable movements. Insomnia, by contrast, is the inability to fall asleep, thus leaving the person feeling tired or impaired the next day. This can occur at any age and is most closely related to being hyperaroused. This can occur as a result of stress, depression, or many other causes. The best treatment is cognitive behavioral therapy and sleep hygiene.
Sleep is something that most people seem to take for granted; but given that close to 70 million adults in the US have a sleep disorder, is good sleep something we actually have to work for, particularly as we age?
Like anything in life, some people can achieve their goals naturally, and others need help. The need for help may be either constant (e.g., using continuous positive airway pressure, or CPAP, for obstructive sleep apnea) or intermittent (e.g., for stress-induced insomnia). As people age, they have a higher incidence of all sorts of disorders. Among the things that happen with age is loss of the neurons in the part of the brain called the hypothalamus that help us fall asleep. We found that loss of these neurons is correlated with more fragmented sleep and less time spent in consolidated sleep. People with dementia of the Alzheimer type lose even more of these neurons than healthy older people, which may account for their difficulties maintaining a normal wake-sleep cycle.
Diet and sleep seem to be very closely related, and there are theoretical remedies on how to get a better night’s sleep, such as taking melatonin, refraining from alcohol before bed, avoiding late-night meals, etc. What are some proven strategies to help people fall and stay asleep?
All of the things you mention–except melatonin–are part of sleep hygiene, which is the best proven way to help people fall and stay asleep. These include having a planned time in bed for eight hours every day, with a fixed bedtime and wake time; not using the bed for anything except sleep and sex; having regular meals without late night eating; turning down the lights about two to three hours before bedtime to maximize natural melatonin secretion; not engaging in rousing activities for the hour before bed. Taking extra melatonin beyond this has very little value (except in certain diseases, such as Parkinson’s disease, where natural melatonin secretion is impaired).
People talk about wanting to change their circadian rhythm to become more of a “morning person,” for example. Is this really possible?
The chronotype of a person, whether they are a “lark” who is best in the morning or an “owl” who is best late at night, is probably set by our genes. Within the range that our genes will let us change, the best way to regularize your circadian rhythms is to practice good sleep hygiene.
Can you talk about your lab’s research?
We are studying sleep and circadian circuitry in the brain. Within the last decade we have identified a number of new cell groups in the brain that participate in promoting wakefulness or sleep. We are just beginning to understand how they interact, and what may happen to them in a variety of diseases.
For example, we are now working on a circuit that controls waking up during sleep apnea. In sleep apnea, people have lax muscle tone in their airway, which collapses (particularly when they lie on their back to sleep). This creates an apnea, or an inability to breathe. After about 20 seconds, this wakes the person up and they start breathing again. Those wakeups are life saving, but also leave the person feeling drained in the morning. We have identified a specific cell cluster in the brain that is responsible for waking the brain up during apnea. The same circuit probably wakes you up when you have pain during the night.
Another circuit we are studying is one that controls the circadian rhythm of aggression. Male mice typically attack another male mouse placed in his cage, but they do this much more often at the end of their wake cycle than at the end of their sleep cycle. We traced a circuit from the suprachiasmatic nucleus, the brain’s biological clock, that we think mediates the circadian propensity to be aggressive.
Unsure of how much sleep your body needs? NIH suggests keeping a “sleep diary” to log sleep quality and paying attention to your body’s signals that it’s time for rest. To get involved with Sleep Awareness Week, join the National Sleep Foundation’s campaign using #SleepBetterFeelBetter; and make sleep a priority to improve your overall health!