Eight hours a night is widely known as the optimal amount of sleep for a healthy body and mind. However, few of us are meeting this standard.

Between work, family, and social lives, going to bed early can seem nearly impossible. Indeed, a recent poll shows that half of Americans get less than seven hours of sleep on average.

Many people try to compensate for their lack of nightly Zs by taking naps or sleeping late on the weekends. The idea of having a ‘sleep debt’ that can be paid off in increments is commonly held. But wrong.

Anyone who has ever taken a nap can attest to how amazingly relaxed and at ease one feels afterwards. Yet a nap is only good for you if it is for 20-30 minutes. Any longer and you will begin to disrupt your night’s sleep.

Moreover, a desire to nap every day could be a sign of a serious health issue, especially in countries where siestas are uncommon.

“Habitual daytime naps are more likely to be indicative of sleep deficiency, chronic … disruption, or a disorder such as obstructive sleep apnea, depression or cancer,” said Charles Czeisler, chief of the Division of Sleep and Circadian Disorders at the Brigham and Women’s Hospital, in Boston.

Czeisler does not wish to imply that naps are dangerous. However, people who feel compelled everyday could very well be suffering from a subtle physical or mental disorder.

“[Regular] napping is associated with increased risk of disease,” said Professor Francesco Cappuccio of the University of Warwick, in the UK.

Hitting the snooze button on the weekends is just as problematic.

“That’s an attempt to pay-back sleep deprivation,” said Czeisler. “It’s a form of sleep bulimia with this chronic binging.”

This so called ‘sleep binging’ breaks the consistency of nightly REM cycles and can, like naps, lead to serious sleep disruptions.

People who sleep late everyday are not off the hook either. Cappuccio lead a study in the UK that looked at the sleep habits of 42 to 81-year olds. The results showed that, over the four years the study was running, participants who slept more than eight hours a night were had a 46 percent higher risk of stroke.

“If you sleep a lot for no reason you should probably contact your doctor,” said Cappuccio.

Prolonged hours of sleep could be indicative of heart conditions as well as depression, infection, inflammatory conditions, and even early stages of cancer.

“That doesn’t mean longer sleep causes these diseases,” said Cappuccio. “[It’s] a consequence of disease, not the cause.”

“When I was on college I got an infection … at one point I was sleeping 20 hours a day,” said Czeisler, a Harvard graduate at the time of the infection. “My immune system was under attack, which does increase sleep duration.” In this sort of situation, sleep is needed in order to recover.

More research needs to be done to fully understand the links between excessive sleep and poor health. In the mean time, the study authors advise people to strive for consistent sleep patterns of seven to nine hours a night.