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Michal Bechny (Switzerland)

Sleep-Stage Dynamics Predict Current Sleep-Disordered Breathing and Future Cardiovascular Risk

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Common causes:

Hypoxia

Oxidative Stress

Sympathetic Activation

Endothelial Dysfunction

Metabolic Dysfunction

Physiological impact:

Atherosclerosis

Cardiovascular

morbidity & mortality:

  • Hypertension,
  • Heart failure,
  • Myocardial Infarction,
  • Stroke,...

Sleep Disordered Breathing (SDB)

Altered SLEEP:

Macro-structure = composition/duration of sleep-stages:

  • ⬆: Light (N1, N2), WASO
  • ⬇: Deep (N3), REM, sleep efficiency, TST

Polysomnography (PSG)

Dynamics = temporal order or transitions of sleep-stages

  • ⬆: Awakenings, (Atypical) Transitions
  • ⬇: Stage-continuity (REM➡REM, N3➡N3)

Can we predict?

[1-10]

[11-15]

[23-27]

Association with

⬇REM, N3 and extreme TST

[16-22]

[28-40]

Dynamics captures detailed physiological signatures

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YES!

Simple physiological / statistical chain implies that

sleep (macrostructure + dynamics) and cardiovascular events

are correlated

correlation ≠ causation

Sleep can be a marker of future cardiovascular events

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Cardiovascular Events:

Up to 15 years follow-up

Benefits of R(S)F:

  • Robust to multicollinearity
  • Flexible to capture interactions & non-linear effects
  • Explainable via partial effects

Machine Learning (AI) models:

  1. Random Forest (RF) classifier
  2. Random Survival Forest (RSF)

Data from Sleep Heart Health Study (SHHS)

Baseline (SHHS1)

  • N = 5,791, Age 39-90
  • “General” population

PSG

Follow-up (SHHS2)

  • N = 2,651
  • 3-5 years later

PSG

Primary data: SHHS1(E = 0, M = 0)

  • Subset of SHHS1; N = 2,579
  • E = 0: prior events-free
  • M = 0: medication-free (𝛼,β- blockers, psychopharmaca, diuretics, aspirin,...)

{

Pooled event

Predictors (X):

  • Common risk-factors: age, gender, BMI, smoking
  • Sleep macrostructure: TST, WASO, (sleep, N3, REM)-latencies
  • Sleep-stage dynamics: 25 transitions proportions [%]

Predictive outcomes (Y):

  • Presence of moderate-to-severe SDB (AHI > 15)
  • Long-term cardiovascular risk (time-to-event, censored)

1.

2.

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Results 1: Identification of moderate-to-severe SDB using RF

SDB can be reliably detected from sleep-stage patterns (macrostructure+dynamics) and common risk factors

1.

2.

Performance (AUROC):

  • SHHS1(E = 0, M = 0): 76.1%
  • {REM, NREM, Mixed}-dominant phenotypes: 74.1-79.4%
  • Remaining SHHS1/2 strata (E = 1 or M = 1): 69.5-80.6%
  • Clinical cohort (BSWR) with sleep disorders: 76.0 %

Capability to identify SDBability to predict cardiovascular risk (?)

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Results 1: Identification of moderate-to-severe SDB using RF

SDB can be reliably detected from sleep-stage patterns (macrostructure+dynamics) and common risk factors

Mostly monotonic risk-profiles (= effects) of predictors for SDB

Performance (AUROC):

  • SHHS1(E = 0, M = 0): 76.1%
  • {REM, NREM, Mixed}-dominant phenotypes: 74.1-79.4%
  • Remaining SHHS1/2 strata (E = 1 or M = 1): 69.5-80.6%
  • Clinical cohort (BSWR) with sleep disorders: 76.0 %

Capability to identify SDB ≈ ability to predict cardiovascular risk (?)

Probability (AHI > 15)

(i) Sigmoidal effects of aging and BMI:

Probability (AHI > 15)

(ii) Stage-specific (N1, N2) awakenings

indicate up to 8% increased SDB-risk

Probability (AHI > 15)

(iii) Continuities of restorative states, P(N3→N3), P(REM→REM), are reduced

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Results 2: Prediction of long-term cardiovascular risk using RSF

Cardiovascular risk can be reliably predicted from sleep-stage patterns (macrostructure+dynamics) and common risk factors

Performance (C-index):

  • SHHS1(E = 0, M = 0): 73.3%
  • SHHS1/2 strata with medications: 64.9-79.3%
  • For subjects with prior events: not so good

Same performance (±1%) as with including AHI predictor!

lower = better

higher = better

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Results 2: Prediction of long-term cardiovascular risk using RSF

Cardiovascular risk can be reliably predicted from sleep-stage patterns (macrostructure+dynamics) and common risk factors

Performance (C-index):

  • SHHS1(E = 0, M = 0): 73.3%
  • SHHS1/2 strata with medications: 64.9-79.3%
  • For subjects with prior events: not so good

Same performance (±1%) as with including AHI predictor!

Non-linear, often U-shaped, risk-profiles (extending [16-22]):

  • = DIGITAL BIOMARKERS for early risk-stratification or screening

“Both sleep and insomnolency, when immoderate, are bad.”

Hippocrates, 400 B.C.E.

10 yr event-free probability

10 yr event-free probability

10 yr event-free probability

Main effect of age Optimal BMI at 20-25 Higher risk for ♂ Congrats to ex-smokers!

Rare transitions are highly sensitive markers, associated +10% risk (vs. 2-3% for smoking)

10 yr event-free probability

U-Shape effects also for REM/N3, excessive amounts may be harmful

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Conclusions

  • Sleep-stage characteristics predict current SDB and future cardiovascular risk.
  • Monotonic risk-profiles for SDB vs. U-Shaped for cardiovascular events suggest distinct root-causes and physiological optima.
  • Certain transitions are sensitive digital markers of SDB/cardiac risk.
  • Sleep assessment can extend cardiovascular risk scales (e.g., FRS, SCORE2).
  • Despite lower precision in comparison to PSG, wearables offer huge potential.

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Thanks for your attention!

Francesca

Faraci

Claudio

Bassetti

Julia

van der Meer

Markus

Schmidt

Athina

Tzovara

Marco

Scutari

Akifumi

Kishi

Yasuhiro Tomita

Michal Bechny

bechnymichal@gmail.com

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References:

SDB and cardiovascular risk:

  1. Peppard, P. E. et al. Prospective study of the association between sleep-disordered breathing and hypertension. New Engl. J. Medicine 342, 1378–1384 (2000).
  2. Leung, R. S. & Douglas Bradley, T. Sleep apnea and cardiovascular disease. Am. journal respiratory critical care medicine 164, 2147–2165 (2001).
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SDB & sleep-macrostructure:

  1. Vgontzas, A. N. et al. Sleep apnea and sleep disruption in obese patients. Arch. internal medicine 154, 1705–1711 (1994).
  2. Kimoff, R. J. Sleep fragmentation in obstructive sleep apnea. Sleep 19, S61–S66 (1996).
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Sleep-macrostructure and cardiovascular risk:

  1. Fung, M. M. et al. Decreased slow wave sleep increases risk of developing hypertension in elderly men. Hypertension 58, 596–603 (2011).
  2. Javaheri, S. et al. Slow-wave sleep is associated with incident hypertension: the sleep heart health study. Sleep 41, zsx179 (2018).
  3. Heslop, P., et al. Sleep duration and mortality: the effect of short or long sleep duration on cardiovascular and all-cause mortality in working men and women. Sleep medicine 3, 305–314 (2002). Note: SELF-REPORTED ASSESSMENT.
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  5. Kwok, C. S. et al. Self-reported sleep duration and quality and cardiovascular disease and mortality: a dose-response meta-analysis. J. Am. Hear. Assoc. 7, e008552 (2018). Note: SELF-REPORTED ASSESSMENT.
  6. Leary, E. B. et al. Association of rapid eye movement sleep with mortality in middle-aged and older adults. JAMA neurology 77, 1241–1251 (2020).
  7. Ai, S. et al. Association of disrupted delta wave activity during sleep with long-term cardiovascular disease and mortality. J. Am. Coll. Cardiol. 83, 1671–1684 (2024).

SDB & sleep-dynamics:

  1. Penzel, T., Kantelhardt, J. W., Lo, C.-C., Voigt, K. & Vogelmeier, C. Dynamics of heart rate and sleep stages in normals and patients with sleep apnea. Neuropsychopharmacology 28, S48–S53 (2003).
  2. Chervin, R. D., Fetterolf, J. L., Ruzicka, D. L., Thelen, B. J. & Burns, J. W. Sleep stage dynamics differ between children with and without obstructive sleep apnea. Sleep 32, 1325–1332 (2009).
  3. Bianchi, M. T. et al. Probabilistic sleep architecture models in patients with and without sleep apnea. J. sleep research 21, 330–341 (2012).
  4. Wächter, M. et al. Unique sleep-stage transitions determined by obstructive sleep apnea severity, age and gender. J. sleep research 29, e12895 (2020).
  5. Bechny, M. et al. Novel digital markers of sleep dynamics: causal inference approach revealing age and gender phenotypes in obstructive sleep apnea. Sci. Reports 15, 12016 (2025).

Sleep dynamics as a physiological marker beyond SDB:

  1. Kemp, B. & Kamphuisen, H. A. Simulation of human hypnograms using a markov chain model. Sleep 9, 405–414 (1986).
  2. Yassouridis, A., Steiger, A., Klinger, A. & Fahrmeir, L. Modelling and exploring human sleep with event history analysis. J. Sleep Res. 8, 25–36 (1999).
  3. Lo, C.-C. et al. Dynamics of sleep-wake transitions during sleep. Europhys. Lett. 57, 625 (2002).
  4. Burns, J. W., Crofford, L. J. & Chervin, R. D. Sleep stage dynamics in fibromyalgia patients and controls. Sleep Medicine 9, 689–696 (2008).
  5. Kishi, A.,et al. Dynamics of sleep stage transitions in healthy humans and patients with chronic fatigue syndrome. Am. J. Physiol. Regul. Integr. Comp. Physiol. 294, R1980–R1987 (2008).
  6. Kim, J. et al. Markov analysis of sleep dynamics. Phys. Rev. Lett. 102, 178104 (2009).
  7. Laffan, A. et al. Utility of sleep stage transitions in assessing sleep continuity. Sleep 33, 1681–1686 (2010).
  8. Kishi, A., Natelson, B.H., Togo, F., Struzik, Z.R., Rapoport, D.M., Yamamoto, Y.: Sleep-stage dynamics in patients with chronic fatigue syndrome with or without fibromyalgia. Sleep 34(11), 1551–1560 (2011)
  9. Wei, Y. et al. Sleep stage transition dynamics reveal specific stage 2 vulnerability in insomnia. Sleep 40, zsx117 (2017).
  10. Yetton, B. D. et al. Quantifying sleep architecture dynamics and individual differences using big data and bayesian networks. PloS one 13, e0194604 (2018).
  11. Kishi, A. et al. Sleep stage dynamics in young patients with sleep bruxism. Sleep 43, zsz202 (2020).
  12. Hermans, L. W. et al. Representations of temporal sleep dynamics: Review and synthesis of the literature. Sleep Med. Rev. 63, 101611 (2022).
  13. Bechny, M. et al. Unveiling sleep dysregulation in chronic fatigue syndrome with and without fibromyalgia through bayesian networks. In International Conference on Artificial Intelligence in Medicine, 33–43 (Springer, 2025)

SHHS study:

  • Quan, S. F. et al. The sleep heart health study: design, rationale, and methods. Sleep 20, 1077–1085 (1997).

Michal Bechny

bechnymichal@gmail.com

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