Font Size
A
A
A

Sleep: Understanding the Basics (cont.)

Sleep Deprivation

Because the function of sleep has not been fully determined, the exact number of hours that a person should sleep is unknown. Some persons claim to work optimally with only 3 to 5 hours of sleep per night, while some admit needing at least 8 hours of sleep per night (or more) to perform effectively. Therefore, sleep deprivation is best defined by group means and in terms of the tasks impaired.

In tasks requiring judgment, increasingly risky behaviors emerge as the total sleep duration is limited to 5 hours per night. The high cost of an action is seemingly ignored as the sleep-deprived person focuses on limited benefits. These findings can be explained by the fact that metabolism in the prefrontal and parietal associational areas of the brain decrease in individuals deprived of sleep for 24 hours. These areas of the brain are important for judgment, impulse control, attention, and visual association.

Sleep deprivation is a relative concept. Small amounts of sleep loss (for example, 1 hour per night over many nights) produce subtle cognitive impairment, which may go unrecognized. More severe restriction of sleep for a week leads to profound cognitive deficits, which may also go unrecognized by the individual. If you feel drowsy during the day, fall asleep for very short periods of time (5 minutes or so), or regularly fall asleep immediately after lying down, you are probably sleep-deprived.

Many studies have made it clear that sleep deprivation is dangerous. With decreased sleep, higher-order cognitive tasks are impaired early and disproportionately. On tasks used for testing coordination, sleep-deprived people perform as poorly as or worse than people who are intoxicated. Total sleep duration of 7 hours per night over 1 week has resulted in decreased speed in tasks of both simple reaction time and more demanding computer-generated mathematical problem solving. Total sleep duration of 5 hours per night over 1 week shows both a decrease in speed and the beginning of accuracy failure.

Total sleep duration of 7 hours per night over 1 week leads to impairment of cognitive work requiring simultaneous focus on several tasks. In driving simulations, for example, accidents increase progressively as total sleep duration is decreased to 7, 5, and 3 hours per night over 1 week. Driver fatigue is responsible for an estimated 100,000 motor vehicle crashes and 1,500 deaths each year, according to the National Highway Traffic Safety Administration.

Since drowsiness occurs just before falling asleep, driving while drowsy often leads to disaster.

According to the National Sleep Foundation "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." It is important to know that caffeine and other stimulants cannot overcome the effects of severe sleep deprivation. Therefore, if you find yourself driving in a sleep-deprived state, it is imperative that you find a safe place to stop and catch up on your sleep before continuing safely on your way.

Medically Reviewed by a Doctor on 9/28/2012
Author:
Coauthor:

Must Read Articles Related to Sleep: Understanding the Basics

Bedwetting
Bedwetting Bedwetting (nocturnal enuresis) is the involuntary passage of urine while sleeping. Causes of bedwetting include urinary tract infection, diabetes, emotional pr...learn more >>
Disorders That Disrupt Sleep (Parasomnias)
Disorders That Disrupt Sleep (Parasomnias) Parasomnias are disruptive sleep-related disorders. They are characterized by undesirable physical or verbal behaviors or experiences. Parasomnias occur in asso...learn more >>
Insomnia
Insomnia Insomnia affects most people at some point in their lifetime. Insomnia is actually a symptoms of a condition, disease, or situation. Non-medical treatment of in...learn more >>

Patient Comments & Reviews

The eMedicineHealth doctors ask about Sleep: Understanding the Basics:

Sleep Problems - Symptoms

What were the symptoms of your sleep problems?

Sleep - Treatment

What helps you to get back to sleep?

Sleep - Problems Experienced

What sleep problems have you experienced?





Read What Your Physician is Reading on Medscape

Sleep Disorder: Problems Associated with Other Disorders »

Sleep disturbances in youth represent highly common phenomena that, in severe forms, can interfere with daily patient and family functioning.

Read More on Medscape Reference »


Medical Dictionary