The average person sleeps 7.5 hours per night and completes four to five sleep cycles. A person’s sleep requirements for good health vary according to age and gender, as well as level of activity during the day. Contrary to conventional wisdom, it is not necessary for all adults to get eight hours of sleep every night to maintain good health. Some people function well with only five hours of sleep, while others may need ten to feel revived in the morning. On the whole, though, most experts recommend approximately eight hours of sleep per day. Infants require the most sleep at 16 to 18 hours a day and young adults generally need about 7.0 to 8.5 hours of shut-eye. As people age, they tend to sleep more lightly and for a shorter duration. The amount of sleep older people need has been debated over the years, but since people over age 55 spend fewer and fewer minutes in Stages 3 and 4, they may need more than eight hours of sleep to experience the restorative powers of deep sleep.
The modern American lifestyle can deter people from getting the sleep they need to function properly. Late nights at the office, shift work, and multiple social and family obligations eat away from the time dedicated to slumber. Many high school students are sleep-deprived—due to the early start times of some schools or trying to do too many activities along with homework—and this may affect their academic abilities. Such factors can run up a high sleep debt, the cumulative amount of time needed to make up for loss of sleep. If you need eight hours of sleep but get only six hours two nights in a row, your total sleep debt will be four hours (2 nights x 2 hours). If you neglect to pay off your sleep debt, you will likely experience mood problems as well as poor cognitive function, which can be detrimental to your health and the health of those around you. According to the National Highway Traffic Safety Administration, driver fatigue (due to sleep deprivation) is responsible for an estimated 100,000 motor vehicle accidents and 1,500 deaths each year.
Though there are tests that doctors use to assess whether you’re meeting your sleep requirements, if you feel alert and emotionally stable with good memory recall and reaction times, you’re probably getting enough sleep. Another clue is sleep latency, the normal length of time it takes you from the time you lie down to the moment you fall asleep. While most people can’t pinpoint the actual moment they fall asleep, you can still estimate. The average sleep latency is between 15 and 20 minutes; falling asleep within five minutes of hitting the sack indicates sleep deprivation. “Microsleeps” very brief periods of sleep (as little as a fraction of a second), are another sign of sleep deprivation. Most people who experience microsleeps aren’t aware of it, but a minor lapse in attention may tip you off to their occurrence. Additionally, feeling drowsy during the day, even during tedious activities, likely means that you haven’t had enough sleep.
