The inhabitants of Vagon Brei had died of a mysterious sleeping sickness, and when SG-1 and medical personnel visited the planet, they too began to exhibit symptoms including an extreme need for sleep and an inability to awaken after falling asleep. In a soil sample taken from the nearby cave, Carter and Dr. Reimer discovered a microscopic parasite. It had remained dormant, however when it came in contact with live tissue, it suddenly became active. Following the death of Dr. Ackerman, Carter and Reimer performed an autopsy and found a ruptured aneurysm near the pineal gland. They also removed from Ackerman's brain a creature identical to the microscopic organism, however it had grown to more than an inch in length. They theorized that the parasite enters the bloodstream and triggers the body's immune response and the production of serotonin. Then it makes its way to the patient's brain, where it lodges and stimulates the production of melatonin. As melatonin floods the body, causing a powerful urge to sleep, the victim slips into an irreversible sleep state and the parasite gorges itself on the melatonin until the surrounding cranial tissue is weakened, eventually provoking a lethal aneurysm. A lizard-like creature on the planet seemed to have a natural immunity to the parasite, and when the creature was captured and brought back to Earth, Dr. Lam was able to produce a serum that cured the illness by isolating the parasite and starving it out.
Cross Reference: Bernard Ackerman, Dr. Grimsby, Dr. Reimer, Sleeping Sickness, Vagon Brei, Vagon Brei Lizard
Episode Reference: Morpheus