Download PDF
Sleep Breath 2001; 05(4): 181-192
DOI: 10.1055/s-2001-18807
COMMENTARY

Copyright © 2001 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel.: +1(212) 584-4662

Sleepiness, Troika of Consciousness Cycle, and the Epworth Sleepiness Scale

Peter T. George
  • Private practice, Honolulu, Hawaii
Further Information

Publication History

Publication Date:
05 December 2001 (online)

    Permissions and Reprints

ABSTRACT

Excessive daytime sleepiness (EDS) is an important indicator when diagnosing sleep-disordered breathing and evaluating its treatment results. However, there appears to be some confusion as to what exactly is sleepiness; Dorland's Illustrated Medical Dictionary does not help. The medical literature was reviewed in order to assemble a schematic model that would suggest a definition of sleepiness and how it can be measured. The derived model is entitled the troika of consciousness cycle (TCC). It assumes that the presence of wakefulness, nonrapid eye movement sleep (NREMS), and rapid eye movement sleep (REMS) is determined by the interactions of four drives: two promoting wakefulness and one each for the two sleep states. The TCC illustrates that inadequate sleep results in sleep debt, but that sleepiness is determined solely by the nearness of the secondary wake drive line to the NREMS drive line. Contact of these lines indicates dozing, a change in consciousness state, an observable event. The probability of this event may be defined as objective sleepiness; this is what the Epworth sleepiness scale (ESS) attempts to measure. Studies indicate that the ESS can determine EDS with greater sensitivity and selectivity than either the multiple sleep latency test or the maintenance of wakefulness test.

KEYWORD

Epworth sleepiness scale - troika of consciousness - multiple sleep latency test - sleep-disordered breathing

REFERENCES

  • 1 WB Saunders Dictionary Staff. Dorland's Illustrated Medical Dictionary 28th ed. Philadelphia, PA: WB Saunders; 1994
  • 2 Dement W C. History of sleep physiology and medicine. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, PA: WB Saunders 2000: 1-14
    Search in Google Scholar
  • 3 Kryger M H, Roth T, Carskadon M. Circadian rhythms in humans: an overview. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 2nd ed. Philadelphia, PA: WB Saunders 1994: 301-308
    Search in Google Scholar
  • 4 Guyton A C. Textbook of Medical Physiology. 8th ed. Philadelphia, PA:WB Saunders; 1991;0:661
  • 5 Daan S, Beersma G M, Borbély A. Timing of human sleep: recovery process gated by a circadian pacemaker.  Am J Physiol . 1984;  246 R161-178
    PubMedSearch in Google Scholar
  • 6 Borbély A A, Achermann P. Simulating the propensity of sleep initiation by the two-process model.  Sleep Res . 1991;  20A 525
    PubMedSearch in Google Scholar
  • 7 Webb W B. Sleep: The Gentle Tyrant.  2nd ed. Bolton, MA: Anker Pub Co 1992: 154-156
    Search in Google Scholar
  • 8 Johns M W. Daytime sleepiness, snoring, and obstructive sleep apnea. The Epworth sleepiness scale.  Chest . 1993;  103 30-36
    CrossrefPubMedSearch in Google Scholar
  • 9 Broughton R J. Chronobiological aspect and models of sleep and napping. In: Dinges DF, Broughton RJ, eds. Sleep and Alertness: Chronobiological, Behavioral, and Medical Aspects of Napping New York, NY; Raven Pr 1989: 71-98
    Search in Google Scholar
  • 10 Lavie P. Ultrashort sleep-waking schedule. III. Gates and ``forbidden zones'' for sleep.  Electroencephalogr Clin Neurophysiol . 1986;  63 414-425
    PubMedSearch in Google Scholar
  • 11 Jones B A. Basic mechanisms of sleep-wake states. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 2nd ed. Philadelphia, PA: WB Saunders 1994: 145-162
    Search in Google Scholar
  • 12 Kleitman N. Basic rest-activity cycle-22 years later.  Sleep . 1982;  5 311-317
    PubMedSearch in Google Scholar
  • 13 Borbély A. Sleep homeostasis and models of sleep regulation. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 2nd ed. Philadelphia, PA: WB Saunders 1994: 309-320
    Search in Google Scholar
  • 14 Knowles J B, Coulter M, Wahnon S. Variations in process S: effects on sleep continuity and architecture.  Sleep . 1990;  13 97-107
    PubMedSearch in Google Scholar
  • 15 Roehrs T, Timms V, Zwyghuizen-Doorenbos A, Roth T. Sleep extension in sleepy and alert normals.  Sleep . 1989;  12 449-457
    PubMedSearch in Google Scholar
  • 16 Carskadon M A, Dement W C, Mitler M M, Roth T, Westbrook P R, Keenan S. Guidelines for the Multiple Sleep Latency Test (MSLT), a standard measure of sleepiness.  Sleep . 1986;  9 519-524
    PubMedSearch in Google Scholar
  • 17 Dement W C. The Sleepwatchers.  Stanford, CA: Stanford Alumni Assoc, 1992: 13-17
    Search in Google Scholar
  • 18 Roth T, Roehrs T, Merlotti L. Ethanol and daytime sleepiness.  Alcohol Drugs Driving . 1990;  6 357-362
    PubMedSearch in Google Scholar
  • 19 Dement W C. Some must watch while some must sleep.  San Francisco, CA: San Francisco Book Co; 1976
    Search in Google Scholar
  • 20 Carskadon M A. Measuring daytime sleepiness. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine 2nd ed. Philadelphia, PA: WB Saunders 1994: 961-962
    Search in Google Scholar
  • 21 Carskadon M A. Alertness. In: Carskadon MA, ed. Encyclopedia of Sleep and Dreaming New York, NY: Macmillan 1993: 24-25
    Search in Google Scholar
  • 22 Sangal R B, Thomas L, Mitler M M. Maintenance of wakefulness test versus multiple sleep latency test: a factor analytic approach.  Sleep Res . 1991;  20 321
    PubMedSearch in Google Scholar
  • 23 Johns M W. A new method for measuring daytime sleepiness: the Epworth sleepiness scale.  Sleep . 1991;  14 540-545
    Search in Google Scholar
  • 24 Johns M W. Rethinking the assessment of sleepiness.  Sleep Med Rev . 1998;  2 3-15
    CrossrefPubMedSearch in Google Scholar
  • 25 Johns M W. Sensitivity and specificity of the multiple sleep latency test (MSLT), the maintenance of wakefulness test and the Epworth sleepiness scale: failure of the MSLT as a gold standard.  . 2000;  9 5-11
    PubMedSearch in Google Scholar
  • 26 Johns M W. Excessive daytime sleepiness. Daytime sleepiness and sleep habits of Australian workers.  Sleep . 1997;  20 844-849
    PubMedSearch in Google Scholar
  • 27 Carskadon M A, Dement W C, Mitler M M, Roth T, Westbrook P R, Keenan S. Guidelines for the multiple sleep latency test (MSLT): a standard measure of sleepiness.  Sleep . 1986;  9(4) 519-524
    PubMedSearch in Google Scholar
  • 28 Benbadis S R, Mascha E, Perry M C, Wolgamuth B R, Smolley L A. Association between the Epworth sleepiness scale and the multiple sleep latency test in a clinical population.  Ann Intern Med . 1999;  130 289-292
    PubMedSearch in Google Scholar
  • 29 Sangal R B, Mitler M M, Sangal J M, and the U.S. Modafinil in Narcolepsy Multicenter Study Group. MSLT, MWT and ESS: indices of sleepiness in 522 drug-free patients with narcolepsy.  Sleep Res . 1997;  26 492
    PubMedSearch in Google Scholar
  • 30 Chervin R D, Aldrich M S, Pickett T, Guilleminault C. Comparison of the results of the Epworth sleepiness scale and multiple sleep latency test.  J Psychosom Res . 1997;  42 145-155
    CrossrefPubMedSearch in Google Scholar
  • 31 U.S. Modafinil in Narcolepsy Multicenter Study Group. Randomized trial of modafinil for the treatment of pathological somnolence in narcolepsy.  Ann Neurol . 1998;  43 88-97
    CrossrefPubMedSearch in Google Scholar
  • 32 Randall S C, Shneerson J M, Smith I E. The Epworth sleepiness scale: widely used and often misinterpreted?.  Sleep . 2001;  24(abstract suppl) A107-108
    PubMedSearch in Google Scholar