Many Americans are so sleepy that they are having problems in their marriages, making mistakes at work and even going without sex, according to a recent report released.

The poll by the National Sleep Foundation found that 75 percent of adults frequently have a symptom of a sleep problem such as frequent waking during the night or snoring. But few believe they have a sleep problem and most ignore it.

"Half of the country sleeps pretty well -- the other half has problems," Foundation chief executive Richard Gelula said in a statement.

What is to blame? The survey of more than 1,500 adults found that 87 percent usually watched TV in the hour before going to bed, 47 percent usually had sex and 64 percent read.

"Only about one-half of respondents are able to say on most nights, 'I had a good night's sleep'," the Foundation, which issues regular reports showing Americans do not get enough sleep, said in a statement.

Nearly a quarter of those in a marriage or relationship said they had sex less often or had lost interest in sex because they are too sleepy.

The Foundation recommends that adults get between seven and nine hours of sleep a night but the survey found that Americans get an average of 6.9 hours.

Of those surveyed, 60 percent of drivers admitted to having driven drowsy in the past year and 4 percent said they had an accident or near-accident because they were tired or dozing while driving.

Almost 30 percent of employed adults said they had missed work, made errors or missed some activity because of sleep-related issues in the past three months.

Most people -- 77 percent -- complained that their partner has a sleep-related problem, usually snoring.

"In my practice, I've found when couples are forced to sleep apart because of one partner's sleep problems, it often has a terrible effect on the relationship," said Dr. Meir Kryger, director of the Sleep Disorders Center at St. Boniface Hospital Research Center at the University of Manitoba in Winnipeg and a director of the Foundation.

More than a third of people who described themselves as poor sleepers said their intimate relationships were affected because they are too sleepy, compared to 8 percent of good sleepers.