Morpheus

Summary
After learning that the Ori have successfully invaded six more planets, SG-1 goes off-world to find an Ancient weapon that Daniel Jackson believes is the key to defeating the Ori. SG-1 and a group of scientists led by Dr. Reimer travel through the gate and discover a village in which all the inhabitants died of a mysterious illness. What is more curious is the fact that most of them seemed to have died in their beds.

But before they can decipher what the cause of this is, they themselves are infected by the plague they come to know as "the curse of Morgan le Fay", which is really a parasite that feeds on melatonin and serotonin. They discover that this induces the urge to sleep, and once the brain falls into its dormant sleep state, the parasite feeds even more and becomes larger and larger until the infected person suffers a fatal stroke. Cameron Mitchell and Teal'c set out to find any sort of cure or treatment for the disease that might exist in the natural environment of the planet, while Jackson and Samantha Carter continue to search for evidence of the weapon that Merlin created to fight the Ori. All are simultaneously fighting a desperate battle to stay awake.

Meanwhile on Earth Vala attempts to cram for her psychiatric evaluation which she worries will be incredibly difficult, even though General Landry assures her it will be very simple. When she finally does take the examination, she is so nervous that she attempts to fake the exam and as a result makes a fool of herself, much to the genuine surprise and bewilderment of the examiner. As Vala continues to worry about her future, she is visited by Richard Woolsey who offers to ensure she passes her evaluation if she agrees to act as a spy by keeping the International Oversight Advisory informed of confidential goings-on at the SGC.

On the parasite planet Teal'c and Colonel Mitchell trek through a forest to search for any animal that might have developed a resistance to the disease. They find one in the form of a strange lizard which is startled and runs into a cave. The pair chase it inside even though they are both on the verge of collapsing from exhaustion. Back at the village, Ackerman dies in his sleep, while Dr. Reimer succumbs of a heart attack due to an overdose of amphetamines and other energy boosting drugs that they are using to stay awake.

Despite all of their efforts Carter and Jackson nearly nod off several times and begin to rely on each other to stay awake. Several hours of hazy exhaustion pass, until a medical team sent to rescue them arrives and seals them in quarantine containers. Carter attempts to tell them of their condition but is too exhausted to speak. Both know that they will probably not be able to resist the urge to sleep any longer.

In the cave Mitchell and Teal'c finally catch up with the lizard, and Teal'c tackles it and catches it in a bag. At this point though Mitchell collapses and is unable to get up, despite many attempts of aid by Teal'c. Teal'c is forced to leave him behind and makes his way up to the entrance of the cave, whereupon he too collapses. The medical team that "helped" Carter and Jackson arrives though, and its at this point that they figure out that the lizard must be a part of a treatment.

The episode shifts back to Earth, where all of the team members seem to be perfectly fine. They talk about how the medical teams were able to synthesize a cure from the lizard and they have spent many hours sleeping - and how Carter and Jackson were able to discover the next clue to the location of Merlin's weapon - Atlantis. They are then informed that there is a situation in the gate room - and upon going there quickly learn that it is Vala, who is demanding that they dial the gate to wherever she wants to go. At this point Landry informs Vala that she really passed the test and that Woolsey's offer was part of it. The episode ends with everyone satisfied (although Woolsey is a bit miffed about Vala's sexual accusation against him), and the team preparing to go to Atlantis for the first time.