Research
Hormonal
Delta sleep-inducing peptide (DSIP), uridine, oxidized glutathione, and muramyl peptides were identified as early 'sleep factors' through transfer experiments, but they lack a determined physiological sleep regulatory role compared to adenosine and PGD2.
Early research identified several substances like DSIP and uridine that could induce sleep when transferred between animals, but their natural role in regulating sleep in the body remains unclear compared to more recently identified factors like adenosine.
ModerateQualifiesMEDIUM confidence
The transfer experiments concluded with the identification of four sleep factors: delta sleep-inducing peptide (DSIP), uridine, oxidized glutathione, and a muramyl peptide. A physiological sleep regulatory role, however, has not been determined for these substances.
Why this rating
Evidence is historical and transfer-based, but physiological role is undetermined.
Source
Biochemical regulation of non-rapid-eye-movement sleep
James M. Krueger · Frontiers in bioscience · 2003
DOI 10.2741/1033
narrative_reviewCited 333×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Adenosine acts as a primary sleep-promoting factor by inhibiting wake-active cholinergic neurons in the basal forebrain via A1 receptors and stimulating sleep-active neurons in the ventrolateral preoptic area (VLPO) via A2 receptors, with extracellular concentrations increasing during wakefulness and decreasing during sleep.Strong
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