From left, panelists Robert Stickgold, John W. Winkelman, Steven W Lockley and Charles A. Czeisler speak at a panel on sleep organized by University Health Services.

“Your mother was right,” a Harvard Medical School professor told undergraduates last night. “If you don’t sleep enough, you’ll get dumb, sick, and fat.”

Associate Professor of Psychiatry Robert A. Stickgold was speaking in Boylston Hall last night as part of a panel assembled by the Community Health Initiative to tell notoriously sleep-deprived Harvard students about the importance of a good night’s sleep.

The panel, composed of sleep experts from the medical school, started out with an issue particularly close to undergraduates’ hearts: all-nighters.

Stickgold said that students who stay up all night perform about 20 percent worse on tasks involving recall than students who get some sleep the night before. This may be because facts are sorted out during sleep, he said, which implies that it’s important to get enough rest the night after studying as well as before.

“The night of sleep you get after you learn something may be even more important than the night of sleep before,” he said.

Another panelist, Steven W. Lockley, who works in the sleep department at Brigham and Women’s Hospital, said that maintaining a regular sleep schedule is just as important as getting the recommended eight to nine hours a night.

“If you constantly have an irregular sleep cycle, you are going to induce jet-lag-like symptoms,” he said.

When a student pulls an all-nighter, this cycle is broken and there will be a number of unpleasant consequences like fatigue and drowsiness.

“When you’ve been awake for 24 hours, you are just as impaired as if you had a blood alcohol level of 0.1 percent,” said the Medical School’s Baldino Professor of Sleep Medicine, Charles A. Czeisler.

But sleeping regular hours isn’t enough to make up for a lack of sleep, the panel said in response to a student’s question about training the body to sleep less.

Just as the body cannot be trained to flourish on 800 calories a day, people cannot teach themselves to function well on just five hours of rest, said Stickgold.

Nor did he condone “sleep bulimia,” the “purging” during the week and “bingeing” on the weekend which he said is a common strategy among students.

The Community Health Initiative invited the professors to speak in response to Harvard students’ rising concerns about getting enough sleep, according to Keli Ballinger, faculty advisor of the initiative.

“Students at Harvard rate sleep as the number two impediment to studying,” she said, calling stress number one.