What Is Normal Sleep?

Normal adults need an average of 8 hours of sleep (range 6 - 10 hours). It is normal to fall asleep within 10 to 20 minutes of going to bed, to wake up spontaneously once or twice in the night then fall back to sleep readily, and wake up feeling refreshed. Children need more sleep and tend to have more deep sleep, while the elderly have more frequent awakenings and less deep sleep. [top]

What Is Good Sleep?
Good sleepers generally have a regular sleep-wake schedules and sleep at least 6-7 hours a night. A good sleeper feels refreshed upon awakening and is able to maintain alertness throughout the day, without the need for an afternoon nap or sleeping in on weekends. [top]

How Much Sleep Is Enough? Sleep needs vary with age. A newborn may need as much as 16-20 hours spread throughout day, an infant may sleep 12-14 hours with most of sleep consolidated to the nocturnal sleep period, while toddlers may require 10 hours or more. Primary school going children should get 9-10 hours of sleep, while teenagers should get 8-9.5 hours. In adults, sleep requirement ranges from 6-10 hours. Although some people take pride in getting by with very little sleep, most people who get fewer than 5-6 hours of sleep are probably not getting enough sleep. [top]

Is Getting Too Little Sleep Harmful?
The serious short and long term consequences of sleep deprivation reflect the important restorative functions of sleep. When we do not get enough sleep, our memory, concentration, alertness and mood are affected. Daytime sleepiness leads to poor school or work performance and can result in serious accidents. Left untreated, long term sleep disturbances decrease quality of life, and can lead to increased morbidity and mortality.

Chronic partial sleep deprivation is probably the most common cause of excessive daytime sleepiness, a problem of “epidemic” proportions according to many sleep experts. With the invention of the light bulb and the availability of many services and entertainment “24/7/365”, people are getting less and less sleep, without realizing how harmful this is to their wellbeing.

The most evident consequence of getting too little sleep is sleepiness. Not only does this impact upon work and school performance, it is potentially life threatening when driving or operating machinery on the job. The most profound impact of sleep deprivation in the body is felt in the brain. Neurological disturbances range from the subtle such as cognitive impairment and memory lapses, to frank hallucinations, blurred vision, ptosis, disorientation, incoordination of body movements and slurred speech. Mood disturbances are also common, with depression being more common in sleep deprived individuals. Impaired performance in monotonous tasks requiring vigilance, such driving and mental tasks involving rote memory, language, numeric skills and high level cognitive tasks are all adversely affected.

Studies have shown that even relatively moderate sleep loss can cause seriously impaired waking neurobehavioural functions in healthy adults and that subjects are typically largely unaware of their increasing cognitive deficits, hence the misconception that sleep deprivation is benign.

While sleep deprivation affects physical functioning less than neurocognitive, there is an impact on cardiovascular, respiratory, endocrine and immune function. For example several epidemiologic studies have found an association between cardiovascular morbidity and chronic sleep restriction. In the Nurses’ Health Study, women sleeping less than 7 hours a night had increased risk of coronary events compared to those averaging 8 hours of sleep a night.

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