Plasticity of the Intrinsic Period of the Human Circadian Timing System
2007

Human Circadian Timing System and Mars Day Adaptation

Sample size: 7 publication 10 minutes Evidence: moderate

Author Information

Author(s): Frank A.J.L. Scheer, Kenneth P. Wright Jr., Richard E. Kronauer, Charles A. Czeisler

Primary Institution: Brigham & Women's Hospital and Harvard Medical School

Hypothesis

Can the human circadian pacemaker be entrained to non-24-hour rest-activity cycles?

Conclusion

The study found that exposure to moderately bright light can effectively entrain the human circadian pacemaker to both a 24.65-hour Martian sol and a 23.5-hour day length.

Supporting Evidence

  • Moderately bright light exposure was effective for entraining individuals to the Martian sol.
  • Intrinsic circadian period was significantly longer after entrainment to the Martian sol compared to the 23.5-hour day.
  • The study demonstrated for the first time plasticity of the human circadian timing system.

Takeaway

This study shows that light can help our bodies adjust to different day lengths, like those on Mars, which is important for astronauts.

Methodology

The study used a randomized, within-subject, crossover design with controlled light exposure to assess circadian period changes.

Limitations

The study was limited to a small sample size and short duration of exposure to non-24-hour cycles.

Participant Demographics

Seven healthy young men aged 22-40 years.

Statistical Information

P-Value

0.002

Confidence Interval

95% CI: 23.46–23.53 h

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1371/journal.pone.0000721

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