Medical Mystery: The Boy Who Couldn't Sleep Since birth, Rhett Lamb, 3, has struggled to get a good night's sleep.

May 10, 2008  -- Rhett Lamb, 3, is often irritable, but it's not just the routine growing pains of a toddler's life that has affected him. It's the fact that Rhett can't sleep.

"We went to the doctor after he was born, and I kept telling him something was wrong. He didn't sleep. They thought I was being kind of an anxious mom, and we went back and forth," Rhett's mother, Shannon Lamb, said. "Finally, they [were] starting to realize now that he really doesn't sleep at all. But we've had a lot of different diagnoses and nobody really knows."

His sleep deprivation caused made him very irritable.

"That's going to have a great impact on his behavior during the day -- his irritability, his ability to eat -- and I'm sure it also impacted the parents tremendously," said Marie Savard, an ABC News medical consultant.

Rhett is awake nearly 24 hours a day, and his condition has baffled his parents and doctors for years. They took clock shifts watching his every sleep-deprived mood to determine what ailed the young boy.

After a number of conflicting opinions, Shannon and David Lamb finally learned what was wrong with their child: Doctors diagnosed Rhett with an extremely rare condition called chiari malformation.

"The brain literally is squeezed into the spinal column. What happens is you get compression, squeezing, strangulating of the brain stem, which has all the vital functions that control sleep, speech, our cranial nerves, our circulatory system, even our breathing system," Savard said.

In order to relieve the pressure on Rhett's brain stem, doctors performed surgery this week that they hope will allow him to sleep properly for the first time in his life. Surgeons made an incision at the base of Rhett's skull to the top of his neck and removed the bone around the brain stem and spinal cord, which produced more space.

"Doing the decompression, relieving that pressure, should absolutely improve those symptoms," Savard said.

Still, doctors said the Lambs may not see major changes for several months or possibly even a year. But Rhett's parents hope their son will be able to get some rest and be normal.

"There is a 50-50 chance that the sleep will improve," Shannon Lamb said. "Once the sleep improves, we can work on the behavioral stuff. He's very irritable all of the time.

"I would love to see him play and have a good time and be happy," she said.