As a species, humans spend about a third of their lives sleeping. That might not be surprising, considering that sleep allows the body to recover from the activities of the two thirds spent awake.
Sleep is as basic a need a need as a eating and drinking, and is necessary for our physical (and some research would suggest, mental) well-being.
How Much Sleep is “Enough”?
The primary role of sleep is to replenish the body’s energy supplies that have been used throughout the day. There are number of factor that have associated with sleep patterns in humans, but some of the main categories include age, a person’s physical size, size, muscle mass, brain size, and present level of physical fitness.
The amount of sleep a person needs per day changes over the course his or her lifetime. In addition, the amount of sleep each person needs varies.1 According to the National Institute of Health, average sleep ranges for different age groups are:
- Newborns 16-18 hours a day
- Preschool-aged children 11-12 hours a day
- School-aged children At least 10 hours a day
- Teens 9-10 hours a day
- Adults (including the elderly) 7-8 hours a day.
Physical labor seems to increase the need for sleep more than intellectual work; however, a combination of both leads to the greatest need for sleep, likely due to simultaneous fatigue among several systems in the body. Not surprisingly, some research suggests that people who perform very high levels of physical and intellectual activity need more sleep than what is considered “normal” for their age group in a 24-period to fully recuperate. While increasing the level of physical exercise has been found to help people who experience insomnia–a prolonged inability to get enough sleep–the result may not be as quick as they might expect.2
Managing to Sleep
What are a few hours–here or there–of lost sleep? In a larger accounting, lost sleep, intentional or otherwise, has a cumulative effect. The total sleep lost is sometimes referred to as “sleep debt”. For example, if someone were to lose 2 hours of sleep each night for a week, the net result is a 14-hour sleep deficit. Some people take naps as a way to manage sleepiness or make up for sleep they may have lost. And while naps can provide a short-term boost in alertness and performance, they don’t come with all the benefits of a longer, night-time sleep.
Factors Affecting Sleep
Medications – Insomnia is a side effect of many common medications, including over-the-counter preparations that contain caffeine. People who suspect their medications are causing them to lose sleep should check with their physician.2
Alcohol – For some people, alcohol can induce drowsiness. After all, it is classified as a depressant. But alcohol also suppresses deep sleep, leads to sleep fragmentation, and relaxes the upper airway muscles, which can exacerbate snoring and the severity of obstructive sleep apnea.
Aside from its negative impact on sleep quality and quantity, alcohol reduces intellectual performance during waking periods. Those who drink themsevles to sleep on occasion, such as at the end of a particularly stressful day, should bear in mind that alcohol is quickly metabolized, and will lead to a ‘rebound’ effect that will significantly increase chances of waking up during the night, cutting down on the chances of receiving a restful sleep.
Caffeine – This stimulant likely needs no introduction. In terms of sheer popularity, caffeine tops the list of substances people in the United States (and many other nations) turn to when seeking to stave off the feeling of drowsiness. Caffeine has a strong effect on the central nervous system by blocking adenosine receptors3, which in effect keeps drowsiness at bay. Commonly ingested sources of caffeine include coffee, tea, chocolate, many carbonated beverages, and some energy drinks. What isn’t as widely known has the potential to be as addictive as what are considered illegal stimulants, such as amphetamines and cocaine. This is due in large part to the fact that they operate by means of similar neurological channels. Caffeine has been widely linked to insomnia, and it fact, it does suppress rapid eye movement (REM) sleep. For this reason alone, it is recommended not to consume caffeine for 6-7 hours before sleep. With our grab-and-go society, this is often easier said than done.
Caffeine use can easily become a vicious circle. A person consumes it for a boost in adrenaline, a sense of energy, and a boost in dopamine. With those results achieved, it’s possible to stay awake longer, sleep less. The “down” side of this cycle is that the person is more sleepy the next day, which in turn drives the urge to counter the effect with, yes, more caffeine. As a result of down-regulation, it will be necessary to continue to raise the amount of caffeine to reach the same ends.
Schedule – Sleeping when the body is ready to sleep is important, but that isn’t always possible due to circumstances. Sometimes a person’s work or daily routine place limits on his or her ability to get enough sleep or to sleep at what are the ‘right’ times for that person. People whose sleep cycle is out of alignment with their body clocks or those whose sleep patterns are routinely interrupted should need to aware of their sleep needs.1
The Bigger Picture
Not having enough greatly reduces a person’s capacity to recover, and therefore the capacity to do perform physical and mental work.
Since society starts with individuals, it’s not surprising that the aggregate effect of a lack of sleep has major implications for public health, safety, productivity, and well-being in society. A growing body of research is looking into the role sleep (or the lack thereof) plays in health and disease. It has been estimated that more than 60 million people in the United States, or approximately one in three adults, experience inadequate sleep that can interfere with daily activities.5
Excessive sleepiness has been associated with accidents at work or at home, and at least three percent of serious automobile accidents and fatalities are due to a fatigued driver.5
Keeping Track of Sleep
No, this isn’t just jotting down how many sheep it takes to count each night to fall asleep. Writing down how much you sleep each night, how alert and rested you feel in the morning, and how sleepy you feel during the day can help to keep track of sleep patterns, including any sleep deficit, and it can serve as record in the event sleep concerns are taken to a healthcare provider.
3. Insomnia:The Facts You Need To Know, http://my.webmd.com/content/article/3462.138
4. Good sleep, good learning, good life,www.supermemo.com/articles/sleep.htm#Exercise
5. National Institute Of Nursing Research, Sleep Deprivation in Healthy Populations. www.nhlbi.nih.gov/health/prof/sleep/sleep99.htm