Normal sleep consists of cycles of non-rapid eye movement (NREM) sleep alternating with rapid eye movement (REM) sleep. NREM sleep consists of light sleep and deep sleep. REM sleep is also known as “dream” sleep. The function of sleep is believed to be restorative, a time of rest and repair for the body.
Adults need an average of 8 hours of sleep (Range of 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.
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 thinking, 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.
Sleep disorders are sleep-related disturbances due to underlying medical problems, lifestyle and environmental factors which usually cause sleep disruption, leading to insufficient or poor quality sleep.
