The Risks of Insufficient Sleep
Getting a good night’s sleep is often more easily said than done. The realities of modern life mean that we have far more distractions and sleep stealers than ever before. We can work, shop, and bank 24 hours a day right from our living rooms.
It doesn’t get easier as we get older. With age, we tend to sleep more lightly and for fewer hours, although our sleep needs don’t change. Contrary to what some sleep-deprived folks may claim, you cannot “train” your body to require less sleep.
You become sleep deprived when you don’t get sufficient sleep to stay alert and function well throughout the day. The effects of sleep deficiency are cumulative. As a result, you can build up a sleep deficit that grows each night you lose sleep and must be paid back.
After several nights of sleep loss—even an hour or two each night—you’ll begin to function in the same way as if you haven’t slept at all for one or two days. If you miss out on two hours of sleep each night, after one week you’ll have accumulated a 14-hour sleep debt. If you routinely don’t get proper sleep, your sleep debt can’t be remedied by sleeping in on weekends.
About half of all people over age 65 have frequent trouble sleeping. Not get- ting adequate sleep can have serious consequences. Sleep deficiency has played a role in several high-profile tragic accidents such as nuclear meltdowns and the grounding of an oil tanker. On our roads, drowsy drivers are responsible for an estimated 100,000 motor vehicle accidents and 1,500 deaths each year, according to the National Highway Traffic Safety Administration. Even more common are the potential day-to-day health consequences from lack of shut-eye. Sleep deficiency is linked with significant physical and mental health effects, including cognitive deficits, cardiac issues, obesity, and impairment of memory and immune function.
Among the most recent research, published online in March 2013 by the European Heart Journal, were findings from an 11-year Norwegian study of more than 54,000 people, ages 20 to 89, that concluded participants with multiple insomnia symptoms had a fourfold increased risk of heart failure compared with those who had no insomnia symptoms.
Researchers found insomnia symptoms were more prevalent among older adults and women. Since this was an observational study, scientists can’t say that insomnia actually causes heart failure, just that there’s an association. More research is needed to learn what the connection is between the two.
Sleep basics
Sleep occurs in cycles. Most people have three to five sleep cycles a night. On average, a complete sleep cycle takes 90 to 110 minutes and consists of five stages:
• Stage 1. Called “light sleep,” you drift in and out of sleep. Eye movements and muscle activity slow, and you may experience a falling sensation.
• Stage 2. Eye movements stop and brain waves (electrical activity fluctuations), slow, with occasional bursts of rapid waves.
• Stage 3. Called “deep sleep,” very slow brain waves called delta waves appear.
• Stage 4. Deep sleep continues in this stage as the brain produces delta waves almost exclusively. No eye or muscle movement occurs. It’s very difficult to wake someone during deep sleep. If you’re woken during deep sleep, you’ll be very groggy and disoriented.
• REM (rapid eye movement). Upon entering REM sleep, so named for the darting eye movements that occur behind closed lids, heart rate and blood pressure increase and limb muscles become immobilized. Dreaming occurs in this stage. REM sleep stimulates areas of the brain involved in learning and is associated with increased protein production.
We spend about half our sleep time in stage 2 and 20 percent in REM sleep, with the remaining 30 percent in the other sleep stages.
What’s adequate sleep?
The amount of sleep an individual needs varies; most adults require seven to eight hours each night. In addition to quantity, sleep quality matters, too. Waking frequently, or fragmented sleep, interrupts the sleep cycle and can contribute to an inability to achieve periods of deep and REM sleep, the stages associated with restful and restorative sleep.
Older adults are at higher risk for sleep deficiency—tending toward fewer sleeping hours and a different sleep-cycle pattern. Deep-sleep stages become very short or stop completely. Several factors likely play a role, including normal aging, medications, or a medical condition that can cause pain or discomfort during the night such as arthritis, hot flashes, frequent nighttime urination, cancer, or lung disease.
A small study published this March in Nature Neuroscience explored the relationship of poor-quality sleep with changes in the brain’s prefrontal cortex (where long-term memories are stored) associated with aging, which both led to reduced slow-wave activity during non-REM sleep.
Researchers concluded that the lack of deep sleep in older adults combined with these structural brain changes is linked to impaired memory and age-related cognitive decline but couldn’t establish a direct, causal connection. Consequences of inadequate sleep
Sleep deprivation is associated with:
• Cognitive impairment. Sleep deficiency impedes learning, focusing, reacting, memory, judgment, decision making, and the ability to perform mathematical computations.
• Poor mental status. Sleep deficiency leads to low energy, decreased libido, and depression and anxiety symptoms, not to mention crankiness and irritability. Sleep problems are common among people with mental illness, and extreme sleep deprivation can trigger paranoia and hallucinations in healthy people.
• Physical health risks. Chronic sleep problems are linked with high blood pressure, stroke, heart disease, heart failure, and diabetes. They’re also associated with an increased risk of falls and broken bones in older adults.
• Immune dysfunction. The ability to fend off viruses like colds is affected by lack of sleep.
• Obesity. Lack of sleep affects the appetite hormones, causing higher levels of the hormone ghrelin, which make you feel hungry, and lower levels of leptin, which make you feel full. This leads to overeating and an increased appetite for high-carbohydrate, calorie-dense foods.
• Declining quality of life. Nearly 40 percent of adults report falling asleep during the day without meaning to, at least once a month. Inappropriate drowsiness and napping, embarrassing enough, may affect relationships. Lack of energy may lead to withdrawal from activities and socializing.
Are you sleep deficient?
So many people suffer from poor sleep that sleep deficiency has become the new normal, and you may not associate the above problems with a lack of sleep. You could be sleep deficient if you often feel as if you might nod off while reading, sitting in a meeting, watching a movie in a theater, or while riding in a car or sitting in traffic.
If you’re experiencing health or cognitive problems that could be related to poor sleep or if you’re not feeling well rested, keep a sleep diary for a few weeks by recording the amount of sleep you get each night and how alert or sleepy you feel during the day. Then show the diary to your doctor, who, after ruling out any underlying medical reasons for poor sleep, should be able to help you.
: : Peter V. Rabins, M.D., M.P.H.
