Kelno'reem is the Jaffa meditation ritual akin to sleep. While the Jaffa meditates, the Goa'uld symbiote repairs any health ailment that the Jaffa suffers from. It can also be used to slow down the Jaffa's heart, and so much that it can beat once per minute, or even stop the heart altogether. In this state the Jaffa is able to communicate with his symbiote, although this kind of communication is forbidden by the Goa'uld as they don't want the Jaffa to influence the minds of their young. Teal'c often lights candles to perform the meditation. Whether other Jaffa do the same is unknown. (SG1: "Holiday", "Descent", "Fallen", "Crossroads")
In 1998, Teal'c was forced to help Colonel Jack O'Neill achieve Kelno'reem after Ma'chello's device switched their bodies, forcing O'Neill to achieve Kelno'reem before Teal'c's body would die from the lack of an immune system. (SG1: "Holiday")
In 2000, Teal'c entered a particularly deep state of Kelno'reem when he and O'Neill were trapped in the X-301 Interceptor after a recall device was activated, hoping that his slowed heartrate would allow them to prolong their remaining life-support to increase their chances of remaining alive long enough to be rescued. (SG1: "Tangent")
When SG-1 were victims of a Memory Stamp on P3R-118, Teal'c was a key part in their escape due to his need to kelno'reem. The standard stamp couldn't properly erase Teal'c's memory, and when a second attempt was made to more thoroughly erase Teal'c's memory, he forgot that he needed to kelno'reem, causing him to collapse as he forgot what he needed to do to keep himself alive. (SG1: "Beneath the Surface")
In 2003, after Teal'c lost his symbiote for good, Teal'c saw no point in attempting to perform the ritual, since the symbiote is often key to Kelno'reem. On the advice of Daniel Jackson – who had been attempting to use the meditation to access dormant memories of his Ascension – Teal'c was able to perform the Kelno'reem again, noting that it helped him to feel better even if he didn't need it anymore. (SG1: "Orpheus")