This, according to researchers at the University of Pennsylvania who have deciphered the chemistry of sleep deprivation on mouse brains. From this work, they've found that limiting an enzyme might someday help mitigate the cognitive consequences of sleep deprivation for people.

While it's hard to imagine that inhibiting this enzyme, phosphodiesterase 4, will knit the raveled sleeve of care or become the new chief nourisher of life's feast, as a noted English writer put it, it might provide a mental power bar for those with illnesses that disrupt the death at each day's end.

While thinkers long before Shakespeare's day understood the importance of sleep for our mental and physical lives, it's only been in the last decade that science has begun to unravel the relationship between sleep and memory, said lead researcher Ted Abel.

For this latest study, Abel and colleagues kept mice awake and then noted changes in their behavior and brains. Then, by giving them phosphodiesterase 4 inhibitors, they were able to restore the tired mice to normal. The results were published last month in the journal Nature.

A drug inhibiting this compound could help people with sleep-disrupting conditions such as schizophrenia and sleep apnea, Abel said. Since it will have some unpleasant side effects, the rest of us are probably better off just snoozing longer.

"If there was any take-home message, it would be that sleep is critical for us and doesn't reflect a kind of weakness," he said. "We have to sleep."

- Faye Flam