Many people view sleep as merely a “down time,” when their brains shut off and their bodies rest. People may cut back on sleep, thinking it won’t be a problem, because other responsibilities seem much more important. But research shows that a number of vital tasks carried out during sleep help people stay healthy and function at their best.
While you sleep, your brain is hard at work forming the pathways necessary for learning and creating memories and new insights. Without enough sleep, you can’t focus and pay attention or respond quickly. A lack of sleep may even cause mood problems. Growing evidence shows that a chronic lack of sleep can also increase your risk of obesity, diabetes, cardiovascular disease, and infections.
Despite growing support for the idea that adequate sleep, like adequate nutrition and physical activity, is vital to our well-being, people are sleeping less. The nonstop “24/7” nature of the world today encourages longer or nighttime work hours and offers continual access to entertainment and other activities. To keep up, people cut back on sleep.
A common myth is that people can learn to get by on little sleep (such as less than six hours a night) with no negative effects. Research suggests, however, that adults need at least seven to eight hours of sleep each night to be well rested. Indeed, in 1910, most people slept nine hours a night. Recent national surveys show that 30 percent of U.S. adults sleep fewer than seven hours a night. As many as 30 percent of adults also report daytime sleepiness so severe that it interferes with work, driving, and social functioning at least a few days each month.
Evidence from other national surveys indicate that 70 percent of adolescents sleep less than the recommended 8 to 9 hours each night. Lack of sleep may have a direct effect on children’s health, behavior, and development.
Not sleeping enough and not sleeping well is not OK. As a matter of fact, there is quite a price to pay. It may surprise you to learn that chronic sleep deprivation, for whatever reason, significantly affects your health, performance, safety, and pocketbook.
There are many causes of sleep deprivation. The, or perhaps we trade sleep for more work or play. We may have medical or
However, it is critically important to realize thatAfter a typical night’s sleep, you may not feel restored and refreshed and be sleepy during the day, but be totally unaware that you are sleep-deprived or have a sleep disorder. You might think, “It’s just the stress of work or the kids,” or you might have “always felt this way” and had no idea that you should feel differently. This lack of awareness compounds the consequences, because so many people remain undiagnosed for years.
That said, let’s look at the consequences of sleep deprivation.
In the short term:
- Decreased Performance and Alertness: Sleep deprivation induces significant reductions in performance and alertness. Reducing your nighttime sleep by as little as one and a half hours for just one night could result in a reduction of daytime alertness by as much as 32%.
- Memory and Cognitive Impairment: Decreased alertness and excessive daytime sleepiness impair your memory and your cognitive ability — your ability to think and process information.
- Stress Relationships: Disruption of a bed partner’s sleep due to a sleep disorder may cause significant problems for the relationship (for example, separate bedrooms, conflicts, moodiness, etc.).
- Poor Quality of Life: You might, for example, be unable to participate in certain activities that require sustained attention, like going to the movies, seeing your child in a school play, or watching a favorite TV show.
- Occupational Injury: Excessive sleepiness also contributes to a greater than twofold higher risk of sustaining an occupational injury.
- Automobile Injury: The National Highway Traffic Safety Administration (NHTSA) estimates conservatively that each year drowsy driving is responsible for at least 100,000 automobile crashes, 71,000 injuries, and 1,550 fatalities.
The good news for many of the disorders that cause sleep deprivation is that after risk assessment, education, and treatment, memory and cognitive deficits improve and the number of injuries decreases. In the long term, the clinical consequences of untreated sleep disorders are large indeed. They are associated with numerous, serious medical illnesses, including:
High blood pressure
Psychiatric problems, including depression and other mood disorders
Attention Deficit Disorder (ADD)
Fetal and childhood growth retardation
Injury from accidents
Disruption of bed partner’s sleep quality
Poor quality of life
Studies show an increased mortality risk for those reporting less than either six or seven hours per night. One study found that reduced sleep time is a greater mortality risk than smoking, high blood pressure, and heart disease. Sleep disturbance is also one of the leading predictors of institutionalization in the elderly, and severe insomnia triples the mortality risk in elderly men.
Remarkably, sleep loss may also be a contributing factor to obesity. John Winkelman, MD, PhD, medical director of the Sleep Health Center at Brigham and Women’s Hospital and assistant professor of psychiatry at Harvard Medical School sums up this finding up nicely: “What most people do not realize is that better sleep habits may be instrumental to the success of any weight management plan.” And Michael Thorpy, MD, director of the Sleep-Wake Disorders Center at Montefiore Medical Center in New York adds, “Any American making a resolution to lose weight … should probably consider a parallel commitment for getting more sleep.”
It is also important to realize the huge scope and prevalence of these disorders; more than 85 sleep disorders are recognized by the American Sleep Disorders Association, affecting more than 70 million Americans. Up to one-third of Americans have symptoms of insomnia; however, less than 10% of those are identified by primary-care doctors. Sleep-related breathing disorders represent a spectrum of abnormalities that range from simple snoring to sleep apnea (repeated episodes of cessation of breathing during sleep). As highly prevalent as they are, most cases remain undiagnosed and untreated.
Chronic snoring, for example, is associated with an increased incidence of heart and brain-related diseases. It is present in about 45% of the U.S. population; up to half of those have sleep apnea.
The prevalence of sleep apnea is on par with diabetes and asthma. More than 20 million Americans — 24% of adult men and 9% of adult women — are estimated to have some degree of obstructive sleep apnea. Only a fraction have been diagnosed and treated.
Sleep apnea is a primary risk factor for high blood pressure; as many as 40% of those people are undiagnosed and untreated for high blood pressure. Effective treatment of sleep apnea in patients with high blood pressure leads to a substantial reduction in stroke risk.
Patients with moderate to severe sleep apnea perform as poorly as drunk drivers and have up to a 15-fold increased risk of motor vehicle accidents.
With the wealth of information and treatment options available for sleep deprivation, much of the suffering, illness from the many related diseases, increase in accident rates, and effects on productivity, performance, concentration, and memory can be avoided. Increased awareness is the first step, for us individually and the health care community. Some researchers suggest that sleep deprivation should be recognized with the same seriousness that has been associated with the societal impact of alcohol.
Myths and Facts about Sleep
Myth 1: Getting just one hour less sleep per night won’t affect your daytime functioning. You may not be noticeably sleepy during the day, but losing even one hour of sleep can affect your ability to think properly and respond quickly. It also compromises your cardiovascular health, energy balance, and ability to fight infections.
Myth 2: Your body adjusts quickly to different sleep schedules. Most people can reset their biological clock, but only by appropriately timed cues—and even then, by one–two hours per day at best. Consequently, it can take more than a week to adjust after traveling across several time zones or switching to the night shift.
Myth 3: Extra sleep at night can cure you of problems with excessive daytime fatigue. The quantity of sleep you get is important, sure, but it’s the quality of your sleep that you really have to pay attention to. Some people sleep eight or nine hours a night but don’t feel well rested when they wake up because the quality of their sleep is poor.
Myth 4: You can make up for lost sleep during the week by sleeping more on the weekends. Although this sleeping pattern will help relieve part of a sleep debt, it will not completely make up for the lack of sleep. Furthermore, sleeping later on the weekends can affect your sleep-wake cycle so that it is much harder to go to sleep at the right time on Sunday nights and get up early on Monday mornings.
How much is enough?
|Average Sleep Needs by Age|
|Newborn to 2 months old||12 – 18 hrs|
|3 months to 1 year old||14 – 15 hrs|
|1 to 3 years old||12 – 14 hrs|
|3 to 5 years old||11 – 13 hrs|
|5 to 12 years old||10 – 11 hrs|
|12 to 18 years old||8.5 – 10 hrs|
|Adults (18+)||7.5 – 9 hrs|
Stages of Sleep:
All sleep is not created equal. Sleep unfolds in a series of recurring sleep stages that are very different from one another in terms of what’s happening beneath the surface. From deep sleep to dreaming sleep, they are all vital for your body and mind. Each stage of sleep plays a different part in preparing you for the day ahead.
- Non-REM (NREM) sleep consists of three stages of sleep, each deeper than the last.
- REM (Rapid Eye Movement) sleep is when you do most active dreaming. Your eyes actually move back and forth during this stage, which is why it is called Rapid Eye Movement sleep.
|The Stages of Sleep|
|Stage N1 (Transition to sleep) – This stage lasts about five minutes. Your eyes move slowly under the eyelids, muscle activity slows down, and you are easily awakened.|
|Stage N2 (Light sleep) – This is the first stage of true sleep, lasting from 10 to 25 minutes. Your eye movement stops, heart rate slows, and body temperature decreases.|
|Stage N3 (Deep sleep) – You’re difficult to awaken, and if you are awakened, you do not adjust immediately and often feel groggy and disoriented for several minutes. In this deepest stage of sleep, your brain waves are extremely slow. Blood flow is directed away from your brain and towards your muscles, restoring physical energy.|
|REM sleep (Dream sleep) – About 70 to 90 minutes after falling asleep, you enter REM sleep, where dreaming occurs. Your eyes move rapidly, your breathing shallows, and your heart rate and blood pressure increase. Also during this stage, your arm and leg muscles are paralyzed.|
Quality Sleep and Your Internal Sleep Cycle:
Your internal 24-hour sleep-wake cycle, otherwise known as your biological clock or circadian rhythm, is regulated by processes in the brain that respond to how long you’ve been awake and the changes between light and dark. At night, your body responds to the loss of daylight by producing melatonin, a hormone that makes you sleepy. During the day, sunlight triggers the brain to inhibit melatonin production so you feel awake and alert.
Your internal clock can be disrupted by factors such as nightshift work, traveling across time zones, or irregular sleeping patterns—leaving you feeling groggy, disoriented, and sleepy at inconvenient times. The production of melatonin can also be thrown off when you’re deprived of sunlight during the day or exposed to too much artificial light at night—especially the light from electronic devices, including TVs, computers, tables, and mobile phones.
You may think that once you go to bed, you soon fall into a deep sleep that lasts for most of the night, progressing back into light sleep in the morning when it’s time to wake up. In reality, the sleep cycle is a lot more complicated.
The amount of time you spend in each stage of sleep changes as the night progresses. For example, most deep sleep occurs in the first half of the night. Later in the night, your REM sleep stages become longer, alternating with light Stage N2 sleep. This is why if you are sensitive to waking up in the middle of the night, it is probably in the early morning hours, not immediately after going to bed.
It’s not just the number of hours in bed that’s important—it’s the quality of those hours of sleep. If you’re giving yourself plenty of time for sleep, but you’re still having trouble waking up in the morning or staying alert all day, you may not be spending enough time in the different stages of sleep.
Each stage of sleep in the sleep cycle offers benefits to the sleeper. However, deep sleep (Stage N3) and REM sleep are particularly important. A normal adult spends approximately 50% of total sleep time in Stage 2 sleep, 20% in REM sleep, and 30% in the remaining stages, including deep sleep.