Getting enough sleep is important for people of all ages to stay in good health. Read more to learn how much sleep you need.
People will often cut back on their sleep for work, for family demands, or even to watch a good show on television. But if not getting enough sleep is a regular part of your routine, you may be at an increased risk for obesity, diabetes, high blood pressure, coronary heart disease and stroke, poor mental health, and even early death. Even one night of short sleep can affect you the next day. Not surprisingly, you’re more likely to feel sleepy. On top of that, you’re more likely to be in a bad mood, be less productive at work, and be involved in a motor vehicle crash.
What is Sleep?
Until the 1950s, most people thought of sleep as a passive, dormant part of our daily lives. We now know that our brains are very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways that we are just beginning to understand.
Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons, in the brain. Neurons in the brainstem, which connects the brain with the spinal cord, produce neurotransmitters such as serotonin and norepinephrine that keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin signaling when we fall asleep. These neurons appear to “switch off” the signals that keep us awake. Research also suggests that a chemical called adenosine builds up in our blood while we are awake and causes drowsiness. This chemical gradually breaks down while we sleep.
Stages of Sleep
During sleep, we usually pass through five phases of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress in a cycle from stage 1 to REM sleep, then the cycle starts over again with stage 1. We spend almost 50 percent of our total sleep time in stage 2 sleep, about 20 percent in REM sleep, and the remaining 30 percent in the other stages. Infants, by contrast, spend about half of their sleep time in REM sleep.
During stage 1, which is light sleep, we drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows. People awakened from stage 1 sleep often remember fragmented visual images. Many also experience sudden muscle contractions called hypnic myoclonia, often preceded by a sensation of starting to fall. These sudden movements are similar to the “jump” we make when startled. When we enter stage 2 sleep, our eye movements stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles. In stage 3, extremely slow brain waves called delta wavesbegin to appear, interspersed with smaller, faster waves. By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together are calleddeep sleep. There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up. Some children experience bedwetting, night terrors, or sleepwalking during deep sleep.
When we switch into REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporarily paralyzed. Our heart rate increases, our blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales – dreams.
Sleep & Sleep Disorder Statistics
Below is a compilation of interesting statistics that relate to sleep and sleep disorders.
Sleep Disorder Statistics:
50-70 million US adults have a sleep disorder.
48.0% report snoring.
37.9% reported unintentionally falling asleep during the day at least once in the preceding month.
4.7% reported nodding off or falling asleep while driving at least once in the preceding month.
Drowsy driving is responsible for 1,550 fatalities and 40,000 nonfatal injuries annually in the United States.
Insomnia is the most common specific sleep disorder, with short-term issues reported by about 30% of adults and chronic insomnia by 10%
25 Million U.S. adults have obstructive sleep apnea
9-21% of women have obstructive sleep apnea
24-31% of men have obstructive sleep apnea
3–5% of the overall proportion of obesity in adults could be attributable to short sleep
Sleep Deprivation Statistics:
37% of 20-39 year-olds report short sleep duration
40% of 40-59 year-olds report short sleep duration
35.3% adults report <7 hours of sleep during a typical 24-hour period.
100,000 deaths occur each year in US hospitals due to medical errors and sleep deprivation have been shown to make a significant contribution.
How Many Hours of Sleep Do I Need?
How much sleep you need changes as you age. The American Academy of Sleep Medicine and the Sleep Research Society recommend:
Habits to improve your sleep
There are some important habits that can improve your sleep health:
- Be consistent. Go to bed at the same time each night and get up at the same time each morning, including on the weekends.
- Make sure your bedroom is quiet, dark, relaxing, and at a comfortable temperature.
- Remove electronic devices, such as TVs, computers, and smart phones, from the bedroom.
- Avoid large meals, caffeine, and alcohol before bedtime.
- Avoid tobacco/nicotine.
- Get some exercise. Being physically active during the day can help you fall asleep more easily at night.
What about sleep quality?
Getting enough sleep is important, but good sleep quality is also essential. Signs of poor sleep quality include feeling sleepy or tired even after getting enough sleep, repeatedly waking up during the night, and having symptoms of sleep disorders (such as snoring or gasping for air). Better sleep habits may improve the quality of your sleep. If you have symptoms of a sleep disorder, such as snoring or being very sleepy during the day after a full night’s sleep, make sure to tell your doctor.
How Important Is Sleep?
People tend to sleep more lightly and for shorter time spans as they get older, although they generally need about the same amount of sleep as they needed in early adulthood. About half of all people over 65 have frequent sleeping problems, such as insomnia, and deep sleep stages in many elderly people often become very short or stop completely. This change may be a normal part of aging, or it may result from medical problems that are common in elderly people and from the medications and other treatments for those problems.
Experts say that if you feel drowsy during the day, even during boring activities, you haven’t had enough sleep. If you routinely fall asleep within 5 minutes of lying down, you probably have severe sleep deprivation, possibly even a sleep disorder. Microsleeps, or very brief episodes of sleep in an otherwise awake person, are another mark of sleep deprivation. In many cases, people are not aware that they are experiencing microsleeps. The widespread practice of “burning the candle at both ends” in western industrialized societies has created so much sleep deprivation that what is really abnormal sleepiness is now almost the norm.
Many studies make it clear that sleep deprivation is dangerous. Sleep-deprived people who are tested by using a driving simulator or by performing a hand-eye coordination task perform as badly as or worse than those who are intoxicated. Sleep deprivation also magnifies alcohol’s effects on the body, so a fatigued person who drinks will become much more impaired than someone who is well-rested. Driver fatigue is responsible for an estimated 100,000 motor vehicle accidents and 1500 deaths each year, according to the National Highway Traffic Safety Administration. Since drowsiness is the brain’s last step before falling asleep, driving while drowsy can – and often does – lead to disaster. Caffeine and other stimulants cannot overcome the effects of severe sleep deprivation. The National Sleep Foundation says that if you have trouble keeping your eyes focused, if you can’t stop yawning, or if you can’t remember driving the last few miles, you are probably too drowsy to drive safely.
Exploding Head Syndrome
Exploding head syndrome (EHS) is a disorder characterized by the perception of loud noises (e.g. a bomb explosion, gunshot or cymbal crash) when going to sleep or awakening. Contrary to the name, ENS is not associated with pain. However the noise attacks can elicit a great deal of fear, confusion and distress in sufferers. Reports of tachycardia and palpitations are also common. Despite the distressing nature of EHS, relatively little is known about the prevalence and underlying cause of the condition. Some scientists have estimated that EHS may affect 10% of the population. Females tend to be more at risk than males and the average age of onset is 50 years old.
There are various theories as to what might cause EHS. For instance, some scientists have speculated that EHS may be associated with minor temporal lobe seizures. Another theory is that EHS is caused by sudden shifts of middle ear components. Other possible causes include stress/anxiety, impairments in calcium signalling and brainstem neuronal dysfunction.
Because of the benign nature of EHS, many individuals do not require medical treatment. However if an individual is suffering from disturbed sleep or considerable distress as a consequence of EHS, then treatment may be necessary. Tricyclic antidepressants have been proven useful in some individuals. Calcium channel blockers may also be beneficial. Non-pharmacological strategies such as relaxation, improved sleep hygiene and counselling may also help to alleviate symptoms.
