Jul 15, 2010

You've heard it a dozen times before -- but how much rest is ideal each day? Researchers believe that is relevant to your age.

Sleep. Why is it so hard to sleep well these days? Hectic lifestyles -- job pressure, deadlines, personal and professional stress -- are factors known to contribute to sleep disorders such as insomnia.

It is important to get plenty of good sleep not only for survival but also for healthy living. A good night's sleep refuels your body with energy, relaxes your brain, and rejuvenates your mind for the next day.

How much sleep do you need?

The amount of sleep you need depends on several factors, for example your age. While infants sleep at least 16 to 18 hours a day, toddlers need much less -- as much as 11 hours, whereas school-going children can do with 10 hours of sleep every night. When you reach your teens, you can do with about nine hours of sleep and by the time you are an adult, seven to eight hours of sleep suffice. Sleep patterns observed in older adults show that they tend to sleep much less -- their sleep is light and they are known to awaken frequently during the night, as compared to younger adults.

As a young adult then, doctors recommend seven to eight hours of sleep every night. But why is sleep of seven to eight hours every night considered adequate when your body may feel rested even after five hours?

Researchers and sleep experts working on establishing the connection between sleep and good health, say that people who sleep less than seven to eight hours a day are less equipped to perform complex mental functions than people who get adequate sleep every night. A good night's sleep, they say, has a positive impact on the physical as well as mental and behavioral health of people, irrespective of age and sex. The quality of sleep you get is as important as the quantity of sleep. If you wake up several times during that time, or toss and turn on your bed, you are most likely going to be drowsy during the next day due to lack of good sleep. Your need for sleep also increases and you end up sleeping in excess of your daily quota if you have been sleep-deprived the previous night.

Is insufficient sleep bad for health?

Fewer hours of sleep are detrimental to your health and eventually impact your longevity. Short sleep, according to the Sleep Foundation of America, is associated with the following risks:

• Increased risk of motor vehicle accidents.
• Increase in body mass index -- a greater likelihood of obesity due to an increased appetite caused by sleep deprivation.
• Increased risk of diabetes and heart problems.
• Increased risk of psychiatric conditions including depression and substance abuse.
• Decreased ability to pay attention, react to signals or remember new information
• Research shows that short or disturbed sleep affects mood, performance and alertness and can result in injury or death.

While short or insufficient sleep affects your longevity, research says there is just as much risk with sleeping too long. Studies show that people who sleep less than six hours a night are as much at risk as those who sleep more than eight hours every night, as against those who sleep seven to eight hours a night and reportedly live the longest.

Sickness is U-shaped, which means both short and long sleep are linked with diseases such as depression, obesity and therefore with heart disease and so on. Scientists are not clear about the cause and effect and whether a short sleeper can live longer by sleeping more or vice versa. But the fact remains when you sleep less, you are less alert, grumpy, lack focus and concentration and more at risk of conditions such as depression, obesity and that of the heart. Continued sleep deprivation is also associated with hallucinations and damage of mental faculties.

How does sleep help?

Sleep relaxes the brain and heals the body. During sleep, the neurons that are active during the day shut down and repair themselves. Sleep allows the brain to exercise synapses that might otherwise break down and weaken due to lack of activity, helps to process new information and organise the old data as it reinforces memory. Scientists say that while sleeping, many of the organs and regulatory systems of our body work actively.

Getting adequate sleep is important because it makes your nervous system function properly. In addition, it heals the bodily organs and helps to boost the immune system. The body, during this time, replaces chemicals and repairs muscles, aging or dead cells and other tissues. During sleep, the body increases its rate of cell division and protein synthesis, aiding in the repair and restoration process.