Evidently, most of us are woefully ignorant about a very basic human function - sleep.

Eighty-six percent of the adult public failed the Sleep IQ Test, administered as part of a national survey. Adult respondents averaged 5.5 out of 12 possible correct responses. The results were released last week by the National Sleep Foundation.Many of us erroneously believe that people need less sleep as they age, that raising the volume on the radio helps people stay awake while driving, that snoring is not harmful as long as it doesn't disturb your sleep, that the human body soon adjusts to night-shift work and that boredom makes us sleepy.

In fact, the human body never adjusts to night work because an internal "biological clock" governs when we feel sleepy or alert, and that clock is regulated by the light and dark cycle. We are "programmed" to feel sleepiest during darkness, regardless of when we work or what the clock says.

The poll to assess public knowledge and attitudes concerning sleep, our own sleep habits and consequences of those habits involved 1,027 adults nationwide.

The consequences of poor and limited sleep are enormous for individual health and productivity as well as for the public health generally but are most dramatic when it comes to the dangers posed by drowsy driving, blamed for more than 100,000 accidents and 76,000 injuries each year.

Yet, 57 percent of those polled admit they sometimes drive when drowsy, and 23 percent say they have fallen asleep at the wheel in the past year.

"Microsleeps," or lapses in attention, can greatly increase the probability of auto accidents, yet 22 percent of those surveyed say they would rather continue driving when very sleepy than take a break at a roadside rest stop because they fear for their safety there.

Of those surveyed, 67 percent report a sleep problem, with one in 13 reporting that a doctor has diagnosed a sleep disorder.

Of the 37 percent who say they experience a level of daytime sleepiness that interferes with daily activities:

- 30 percent report that it interferes with their jobs.

- 25 percent report that it interferes with their family duties.

- 28 percent report that it interferes with their social lives.

- 37 percent report that it interferes with their recreational or leisure activities.

In addition, 9 percent say they have used medication to help them stay awake in the past year.