Entrainment of the human circadian clock.

@article{Roenneberg2007EntrainmentOT,
  title={Entrainment of the human circadian clock.},
  author={Till Roenneberg and Martha Merrow},
  journal={Cold Spring Harbor symposia on quantitative biology},
  year={2007},
  volume={72},
  pages={
          293-9
        }
}
Humans are an excellent model system for studying entrainment of the circadian clock in the real world. Unlike the situation in laboratory experiments, entrainment under natural conditions is achieved by different external signals as well as by internal signals generated by multiple feedbacks within the system (e.g., behavior-dependent light and temperature changes, melatonin levels, or regular nutrient intake). Signals that by themselves would not be sufficient zeitgebers may contribute to… 

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