Sleep and Breathing

, Volume 23, Issue 1, pp 379–388 | Cite as

Atypical sleep in critically ill patients on mechanical ventilation is associated with increased mortality

  • Yuliya BoykoEmail author
  • Palle Toft
  • Helle Ørding
  • Jørgen T Lauridsen
  • Miki Nikolic
  • Poul Jennum
Methods • Original Article


Sleep patterns in critically ill patients’ polysomnographic sleep studies (PSG) are severely abnormal.


We aimed to investigate the association of atypical sleep patterns, micro-sleep phenomena (sleep spindles and K-complexes) and rapid eye movement (REM) sleep with intensive care unit (ICU), in-hospital and 90-day mortality in conscious critically ill patients on mechanical ventilation.


This was a prospective descriptive study. We analysed 52 PSGs recorded in conscious critically ill patients on mechanical ventilation. PSGs were scored according to standard classification when possible. Otherwise, modified classification proposed for scoring sleep in critically ill patients was used. The association of PSG findings with mortality was studied using logistic regression and Weibull model of survival analysis.


The presence of atypical sleep patterns in accordance with modified sleep scoring classification was associated with higher odds for ICU mortality (odds ratio 11.63; p = 0.03). The absence of K-complexes was associated with higher odds for ICU mortality (odds ratio 11.63; p = 0.03), while the absence of sleep spindles was associated with higher odds for in-hospital (odds ratio 7.80; p = 0.02) and 90-day mortality (odds ratio 5.51; p = 0.02). Loss of sleep spindles was associated with higher mortality risk with cutoff point 90 days (hazard ratio 3.87; p = 0.03).


The presence of atypical sleep and absence of normal PSG sleep characteristics in conscious critically ill patients on mechanical ventilation indicates involvement of sleep producing brain structures in the pathological process and is associated with poor outcome.


Polysomnography Sleep scoring classification Atypical sleep Critically ill patients 



Special thanks to the ICU staff, Vejle Hospital and Odense University Hospital, for their great contribution to the project.

Funding information

This study received financial support from the University of Southern Denmark; the Region of Southern Denmark; Department of Anesthesiology and Intensive Care Medicine, Vejle Hospital; The Research Foundation at Vejle Hospital; Department of Anesthesiology and Intensive Care Medicine, Odense University Hospital; Danish Society of Anesthesiology and Intensive Care Medicine; Aage and Viola Holm-Madsens Research Foundation; A.P. Moellers Foundation and Exchange pool Rigshospitalet/Odense University Hospital.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in the study were in accordance with the ethical standards of the national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


  1. 1.
    Hodgson CL, Udy AA, Bailey M, Barrett J, Bellomo R, Bucknall T, Gabbe BJ, Higgins AM, Iwashyna TJ, Hunt-Smith J, Murray LJ, Myles PS, Ponsford J, Pilcher D, Walker C, Young M, Cooper DJ (2017) The impact of disability in survivors of critical illness. Intensive Care Med 43:992–1001. CrossRefGoogle Scholar
  2. 2.
    Ely EW, Shintani A, Truman B, Speroff T, Gordon SM, Harrell FE Jr, Inouye SK, Bernard GR, Dittus RS (2004) Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit. JAMA 291:1753–1762CrossRefGoogle Scholar
  3. 3.
    Stickgold R, Walker MP (2007) Sleep-dependent memory consolidation and reconsolidation. Sleep Med 8:331–343CrossRefGoogle Scholar
  4. 4.
    Palmblad J, Petrini B, Wasserman J, Akerstedt T (1979) Lymphocyte and granulocyte reactions during sleep deprivation. Psychosom Med 41:273–278CrossRefGoogle Scholar
  5. 5.
    Trivedi MS, Holger D, Bui AT, Craddock TJA, Tartar JL (2017) Short-term sleep deprivation leads to decreased systemic redox metabolites and altered epigenetic status. PLoS One 12:e0181978. CrossRefGoogle Scholar
  6. 6.
    Kamdar BB, Needham DM, Collop NA (2012) Sleep deprivation in critical illness: its role in physical and psychological recovery. J Intensive Care Med 27:97–111. CrossRefGoogle Scholar
  7. 7.
    Silber MH, Ancoli-Israel S, Bonnet MH, Chokroverty S, Grigg-Damberger MM, Hirshkowitz M, Kapen S, Keenan SA, Kryger MH, Penzel T, Pressman MR, Iber C (2007) The visual scoring of sleep in adults. J Clin Sleep Med 3:121–131Google Scholar
  8. 8.
    Cooper AB, Thornley KS, Young GB, Slutsky AS, Stewart TE, Hanly PJ (2000) Sleep in critically ill patients requiring mechanical ventilation. Chest 117:809–818CrossRefGoogle Scholar
  9. 9.
    Foreman B, Westwood AJ, Claassen J, Bazil CW (2015) Sleep in the neurological intensive care unit: feasibility of quantifying sleep after melatonin supplementation with environmental light and noise reduction. J Clin Neurophysiol 32:66–74. CrossRefGoogle Scholar
  10. 10.
    Drouot X, Roche-Campo F, Thille AW, Cabello B, Galia F, Margarit L, d’Ortho MP, Brochard L (2012) A new classification for sleep analysis in critically ill patients. Sleep Med 13:7–14. CrossRefGoogle Scholar
  11. 11.
    Watson PL, Pandharipande P, Gehlbach BK, Thompson JL, Shintani AK, Dittus BS, Bernard GR, Malow BA, Ely EW (2013) Atypical sleep in ventilated patients: empirical electroencephalography findings and the path toward revised ICU sleep scoring criteria. Crit Care Med 41:1958–1967. CrossRefGoogle Scholar
  12. 12.
    Bergamasco B, Bergamini L, Doriguzzi T, Fabiani D (1968) EEG sleep patterns as a prognostic criterion in post-traumatic coma. Electroencephalogr Clin Neurophysiol 24:374–377CrossRefGoogle Scholar
  13. 13.
    Claassen J, Hirsch LJ, Frontera JA, Fernandez A, Schmidt M, Kapinos G, Wittman J, Connolly ES, Emerson RG, Mayer SA (2006) Prognostic significance of continuous EEG monitoring in patients with poor-grade subarachnoid hemorrhage. Neurocrit Care 4:103–112CrossRefGoogle Scholar
  14. 14.
    Sutter R, Barnes B, Leyva A, Kaplan PW, Geocadin RG (2014) Electroencephalographic sleep elements and outcome in acute encephalopathic patients: a 4-year cohort study. Eur J Neurol 21:1268–1275. CrossRefGoogle Scholar
  15. 15.
    Boyko Y, Jennum P, Nikolic M, Holst R, Oerding H, Toft P (2016) Sleep in intensive care unit: the role of environment. J Crit Care 37:99–105. CrossRefGoogle Scholar
  16. 16.
    Boyko Y, Jennum P, Oerding H, Lauridsen JT, Nikolic M, Toft P (2018) Sleep in critically ill, mechanically ventilated patients with severe sepsis or COPD. Acta Anaesthesiol Scand 62:1120–1126. CrossRefGoogle Scholar
  17. 17.
    Caporro M, Haneef Z, Yeh HJ, Lenartowicz A, Buttinelli C, Parvizi J, Stern JM (2012) Functional MRI of sleep spindles and K-complexes. Clin Neurophysiol 123:303–309. CrossRefGoogle Scholar
  18. 18.
    Fraigne JJ, Torontali ZA, Snow MB, Peever JH (2015) REM sleep at its core - circuits, neurotransmitters, and pathophysiology. Front Neurol 6:123. CrossRefGoogle Scholar
  19. 19.
    Boyce R, Williams S, Adamantidis A (2017) REM sleep and memory. Curr Opin Neurobiol 44:167–177. CrossRefGoogle Scholar
  20. 20.
    Young GB, McLachlan RS, Kreeft JH, Demelo JD (1997) An electroencephalographic classification for coma. Can J Neurol Sci 24:320–325CrossRefGoogle Scholar
  21. 21.
    Markand ON (2003) Pearls, perils, and pitfalls in the use of the electroencephalogram. Semin Neurol 23:7–46CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.Department of Anesthesiology and Intensive Care MedicineOdense University Hospital, & University of Southern DenmarkOdense CDenmark
  2. 2.Department of Anesthesiology and Intensive Care MedicineVejle HospitalVejleDenmark
  3. 3.Faculty of HealthUniversity of Southern DenmarkVejleDenmark
  4. 4.Department of Business and EconomicsUniversity of Southern DenmarkOdense MDenmark
  5. 5.Danish Center for Sleep Medicine, Department of Clinical NeurophysiologyRigshospitaletGlostrupDenmark
  6. 6.Faculty of HealthUniversity of CopenhagenGlostrupDenmark

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