Muramyl peptides Factor

Numerous analogs of the muramyl peptide factor 153 13+1 have been synthesized with a view to finding endogenous hypnotics that do not lead to dependence. 

Another controversial but exciting area of research is the potential role of serotonin in sleep. 5-Hydroxytryptamine may trigger slow-wave sleep (non-REM sleep), whereas the muscarinic AChR and NE are involved in REM sleep (rapid-eye-movement sleep, paradoxical sleep, dream sleep). In addition to the aminergic regulation of sleep, recent research has identified several other presumed sleep factors delta-sleep-inducing peptide, sleep-promoting substance, interleukin-1, and muramyl peptides. 

Early in the 20th century, Pierin in Paris infused the CSF of sleep-deprived dogs into normal dogs and showed that the CSF contained a sleep-inducing (somnogenic) factor. This was thought to be a muramyl peptide but later suggested to be the result of bacterial contamination as these peptides cannot be synthesized by the mammalian brain. 

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