Research

Hormonal

Low-dose melatonin (0.3 mg) administered before sleep does not improve sleep duration, quality, or structure in astronauts during spaceflight.

Low-dose melatonin (0.3 mg) is not a reliable sleep aid for astronauts in space. While it worked in lab settings, it failed to improve sleep in the operational spaceflight environment. Do not rely on it as a primary countermeasure for sleep loss in high-stress, irregular environments.

GoodRefutesHIGH confidence
Administration of melatonin (0.3 mg) on alternate nights did not improve sleep.
Derk‐Jan Dijk et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2001

Why this rating

Double-blind, placebo-controlled, crossover design, but small sample size (n=5).

Source

Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights

Derk‐Jan Dijk et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2001

DOI 10.1152/ajpregu.2001.281.5.r1647

crossover · n=5Cited 266×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →