SLEEP IS A HEALTHY HABIT that should be habit forming. Oddly, however, people in developed countries seem to be sleeping less (either by choice of force of circumstance) the older they get. A major study showed a third of the population of the United Kingdom and over 40 percent in the U.S. regularly sleep less than five hours a night. That’s not healthy.
A growing body of scientific research about sleep points to several agreements:
- A healthy night’s sleep for an adult means sleeping for six hours to about eight hours. People who sleep within this range tend to lead longer lives, according to some studies. Other findings show sleeping seven hours per night is optimal for health. Surprisingly, sleeping for nine hours or more doesn’t seem good for adults.
- Children, on the other hand, need more daily sleep to develop and function properly. Pre-teens and teenagers need from nine to 11 hours of sleep while newborn babies require up to 18 hours of sleep. Children who don’t sleep well should see a doctor.Lack of sleep (or short sleep or sleep deprivation) could kill you, either through natural or accidental causes.
- Short sleep has been shown as a risk factor for weight gain, hypertension and Type 2 diabetes (sometimes leading to death). Falling asleep while driving is a deadly cause of motor vehicle accidents. Short sleep occurs when you don’t sleep the right amount for your individual needs. You can take an amusing “Sleep Dash Test” at http://www.bbc.co.uk/science/humanbody/sleep/sheep/ to find out how sleep deprived you are.
- Short sleep could be more dangerous for women than men.
Sleep is a natural state where one is totally or partially unconscious. It’s marked by the suspension of sensory or motor activity and insensitivity to external stimuli (which explains why you can’t tickle a sleeping person).
Proper sleep rejuvenates your body and allows it to heal after a day’s exertions because nearly all your voluntary muscles become inactive. It gives your body a chance to rest and prepare for the next day’s physical and mental challenges. Proper sleep helps organize memories and improve concentration (which is especially important for students) and is an argument against cramming. Therefore, the brain suffers the most from the effects of a lack of sleep (memory lapses and decreased concentration, for example) as anyone who has gone without sleep for a day will attest to.
Sleep also helps in the growth and rejuvenation of your immune, muscular, skeletal and nervous systems. For example, without adequate sleep, the immune system weakens and the body becomes more vulnerable to infection and disease, and less able to fight off potentially cancerous cells. Growth hormones vital to children are released during sleep. When your body doesn’t get enough sleep, the damage done to it by your daily activities can’t be repaired and could worsen with each passing day.
The need for proper sleep varies by age and among individuals. It’s considered adequate, however, when you suffer from no daytime sleepiness or dysfunctions such as lack of concentration and poor diet. You should normally be able to fall asleep within 15 minutes of going to bed. If you don’t, get out of bed and perform light physical activities such housework, reading or some exercise. Drinking a glass of milk is a time tested “sleep potion.”
There are two broad types of sleep in people (as well as other mammals and birds): non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM or lighter sleep is a sleep state during which rapid eye movements and dreaming do not occur. It accounts for about 75% of normal sleep time in most human adults. REM or deeper sleep, on the other hand, accounts for about 25% of total sleep time. Most memorable dreaming occurs in this stage. REM sleep also appears to be important in brain development, especially among children.
Lack of Sleep is a Health Risk
Perhaps one of the most telling pro-sleep advocacies was made in 2007 by the World Health Organization (WHO).
In a historic and controversial announcement, WHO’s cancer arm, the International Agency for Research on Cancer, listed “shiftwork that involves circadian disruption” as a probable carcinogen or cancer-causing agent.
This announcement put shiftwork in the same category as other cancer-causing agents like diesel engine exhaust and ultraviolet radiation. The study was published in the December 2007 issue of magazine, The Lancet Oncology.
The shiftwork referred to is the graveyard shift (late night to early morning) that in this country involves medical personnel, call center agents, employees at 24-hour service stores, policemen and night shift workers in factories, among others. One doctor claims one hour of work between 11:00 pm and 5:00 am puts more of a load on a person’s physiological health than any other time of the day.
Scientists believe shiftwork is dangerous mainly because it disrupts the “circadian rhythm” (the body's biological clock). The hormone melatonin that can suppress tumor development and that is responsible for sleep regulation is normally produced at night. It is not widely produced in the day hours because light shuts down its production. Research has found that people working in artificial light at night may have lower melatonin levels, which scientists think can raise their chances of developing cancer.
This announcement by WHO about the dangers caused by sleep disruption is by no means unique, but is by far one of the most widely publicized. Earlier or in September 2007, a British study said people double their risk of dying by not sleeping seven hours a night although the reason for this remains unclear. This study, funded by both the British and U.S. governments, involved 10,000 government workers tracked over a 17-year period. It was the first to link duration of sleep and mortality rates.
Another British study found that women who get less than the recommended eight hours sleep a night are at higher risk of heart disease and heart-related problems than men with the same sleeping patterns. Research by the University of Warwick and University College London provides some insight into a potential mechanism for the observation in previous studies that indicates an increased risk of death from cardiovascular disease in individuals who have less than five hours sleep per night and increased risk of non-cardiovascular death in long sleepers.
The study’s findings add to growing evidence that supports the idea short sleep is associated with an increase in cardiovascular risk, and that the association between sleep duration and cardiovascular risk factors is different in men and women.