Effects of the neuropeptide substance P on sleep, mood, and neuroendocrine measures in healthy young men

What Was Tested

This randomized controlled trial paper looks at Substance P.

The researchers investigated whether SP may induce changes of sleep, mood and neuroendocrine measures that are similar to those in depressed patients.

In a double-blind, randomized cross-over design, 12 healthy young men were investigated in two blocks of three consecutive nights, in which SP or NaCl was intravenously infused during the third night.

Who Took Part

According to the abstract, 12 men were involved.

PubMed indexes the participants as adults, men only.

How the Study Was Run

In design terms this was a randomized, double-blind and crossover study.

Random assignment meant chance, not the researchers, decided who got Substance P and who got the comparison, which limits bias.

As a double-blind Substance P study, the assignments were hidden from both participants and investigators until the end.

In the crossover set-up each of the men took both Substance P and the comparison in turn, acting as their own control.

What Was Measured

The researchers investigated whether SP may induce changes of sleep, mood and neuroendocrine measures that are similar to those in depressed patients.

The subject headings attached to it are Affect, Area Under Curve, Growth Hormone, Hydrocortisone, Neuropeptides, Neurosecretory Systems and Sleep.

What This Means in Plain Language

The paper is a randomized, double-blind and crossover study of Substance P in 12 men.

With fewer than 40 people, it is a small study, so it is better read as an early signal for further research than as a settled answer.

The publication is from 2002 (Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology), a journal based in England.

More context: the Substance P compound page, all human trials.