Sleep Cycle

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A Sleep Cycle is a biological pattern that ...



References

2018

2018b

  • (Wikipedia, 2018) ⇒ https://en.wikipedia.org/wiki/sleep_cycle#Characteristics Retrieved:2018-1-8.
    • Electroencephalography readily shows the timing of sleep cycles by virtue of the marked distinction in brainwaves manifested during REM and non-REM sleep. Delta wave activity, correlating with slow-wave (deep) sleep, in particular shows regular oscillations throughout a good night’s sleep. Secretions of various hormones, including renin, growth hormone, and prolactin, correlate positively with delta-wave activity, while secretion of thyroid-stimulating hormone correlates inversely.[1] Heart rate variability, well-known to increase during REM, predictably also correlates inversely with delta-wave oscillations over the ~90-minute cycle.[2]

       Homeostatic functions, especially thermoregulation, occur normally during non-REM sleep, but not during REM sleep. Thus, during REM sleep, body temperature tends to drift away from its mean level, and during non-REM sleep, to return to normal. Alternation between the stages therefore maintains body temperature within an acceptable range. [3] In humans the transition between non-REM and REM is abrupt; in animals, less so. Researchers have proposed different models to elucidate the undoubtedly complex rhythm of electrochemical processes that result in the regular alternation of REM and NREM sleep. Monoamines are active during NREMS but not REMS, whereas acetylcholine is more active during REMS. The reciprocal interaction model proposed in the 1970s suggested a cyclic give and take between these two systems. More recent theories such as the "flip-flop" model proposed in the 2000s include the regulatory role of in inhibitory neurotransmitter gamma-aminobutyric acid (GABA). [4]


  1. Claude Gronfier, Chantal Simon, François Piquard, Jean Ehrhart, & Gabrielle Brandenberger, “Neuroendocrine Processes Underlying Ultradian Sleep Regulation in Man”, Journal of Clinical Endocrinology & Metabolism 84(8), 1999; doi:10.1210/jcem.84.8.5893.
  2. Gabrielle Brandenberger, Jean Erhart, François Piquard, & Chantal Simon, ”Inverse coupling between ultradian oscillations in delta wave activity and heart rate variability during sleep”; Clinical Neurophysiology 112(6), 2001; doi:10.1016/S1388-2457(01)00507-7.
  3. Pier Luigi Parmeggiani, "Modulation of body core temperature in NREM sleep and REM sleep"; in Mallick et al. (2011).
  4. James T. McKenna, Lichao Chen, & Robert McCarley, "Neuronal models of REM-sleep control: evolving concepts"; in Mallick et al. (2011).