What particular biomedical data did NASA use to determine if an Apollo astronaut was awake or asleep?

From the APOLLO 11 MISSION COMMENTARY, page 72/1 "Our Flight Surgeon reported a short while ago that Command Module Pilot Mike Collins appeared to be sleeping soundly at this time. Biomedical data on the other two crewmen indicates that they are still awake."

If ISS astronauts' sleep is still monitored has the specific data used changed?

  • $\begingroup$ Slightly related: within circadian rhythm body temperature and blood pressure changes between sleep and awake phases. There was experiment "Thermolab" on ISS: astronauts' body temperature was monitored to assess the effect of microgravity on circadian rhythm : link 1, link 2, link 3 $\endgroup$ Commented Jan 23, 2020 at 7:14

1 Answer 1


Here’s a detailed description of the biomedical instrumentation system:


This included heart and respiration monitors. Presumably, sleeping was inferred from slow and steady heartbeat and breathing.

I don’t believe ISS astronauts wear bio monitors on a regular basis.


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