Table 2.
Cytokines and Neurohumoral Regulators of Sleep
| Effect on NREM Sleep | |
|---|---|
| IL-1 | Promotion |
| IL-2 | Possibly promotes* |
| IL-4 | Inhibition |
| IL-6 | Possibly promotes† |
| IL-10 | Inhibition |
| IL-18 | Promotion |
| TNF-α | Promotion |
| TGF-β | Inhibition |
| IGF-1 | Inhibition |
| GHRH | Promotion |
| CRH | Inhibition |
| NO | Promotion |
| Ghrelin | Promotion |
| VIP | Promotion |
Definition of abbreviations: CRH = corticotropin-releasing hormone; GHRH = growth hormone–releasing hormone; IGF = insulin-like growth factor; NREM = non–rapid eye movement; TGF = transforming growth factor; TNF = tumor necrosis factor; VIP = vasoactive intestinal peptide.
*
Sleep induces increased circulating IL-2 levels.
†
May play a more important role in sleep regulation during pathologic states.