While nightmares are most often associated with sleep, for a few the inability to get any sleep is a nightmare in and of itself.
Such is the case with 4-year-old Rhett Lamb, who according to his mother stays awake nearly 24 hours a day.
"We went to the doctor after he was born, and I kept telling him something was wrong. He didn't sleep," Rhett's mother, Shannon Lamb, told ABC News' "Good Morning America."
"They thought I was being kind of an anxious mom, and we went back and forth," she 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."
After a number of conflicting opinions, Rhett's parents 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," said ABC News medical consultant Dr. Marie Savard.
In order to relieve this pressure, doctors earlier this year performed a surgery that would afford more space in the boy's skull for his brain. 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.
Doctors expected results of the surgery, conducted in May, to take up to a year to manifest.
"There is a 50-50 chance that the sleep will improve," 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.
For others with similar sleep-deprivation conditions, a lack of sleep can have serious detrimental health effects. Several studies since 2001 have linked a lack of sleep to heart disease and various mental disorders.