Sami Nikkonen

A comparative analysis of unsupervised machine‐learning methods in PSG‐related phenotyping

Ghorvei, Mohammadreza; Karhu, Tuomas; Hietakoste, Salla; Ferreira‐Santos, Daniela; Hrubos‐Strøm, Harald; Islind, Anna Sigridur; Biedebach, Luka; Nikkonen, Sami; Leppänen, Timo; Rusanen, Matias. 2024. Journal of sleep research. [First published: 24 October 2024]: 1-13 A1 Journal article (refereed), original research

Excessive daytime sleepiness is associated with relative delta frequency power among patients with mild OSA

Howarth, Timothy; Tashakori, Masoumeh; Karhu, Tuomas; Rusanen, Matias; Pitkänen, Henna; Oksenberg, Arie; Nikkonen, Sami. 2024. Frontiers in neurology. 15: . 1367860 A1 Journal article (refereed), original research

Interhemispheric differences of electroencephalography signal characteristics in different sleep stages

Tashakori, Masoumeh; Rusanen, Matias; Karhu, Tuomas; Grote, Ludger; Nath, Rajdeep Kumar; Leppänen, Timo; Nikkonen, Sami. 2024. Sleep medicine. 117: 201-208 A1 Journal article (refereed), original research

Prolonged lung-to-finger circulation time indicates an increased risk of intermittent hypoxaemia in sleep apnoea patients

Pahari, Purbanka; Korkalainen, Henri; Arnardóttir, Erna Sif; Islind, Anna Sigridur; August, Elias; Oksenberg, Arie; Töyräs, Juha; Leppänen, Timo; Nikkonen, Sami. 2024. ERJ open research. 10: . 01051-2023 A1 Journal article (refereed), original research

Respiratory event index underestimates severity of sleep apnea compared to apnea-hypopnea index

Pitkänen, Minna; Nath, Rajdeep Kumar; Korkalainen, Henri; Nikkonen, Sami; Mahamid, Alaa; Oksenberg, Arie; Duce, Brett; Töyräs, Juha; Kainulainen, Samu; Leppänen, Timo. 2024. Sleep advances. 5: . zpad054 A1 Journal article (refereed), original research

Retrospective validation of automatic sleep analysis with grey areas model for human‐in‐the‐loop scoring approach

Rusanen, Matias; Jouan, Gabriel; Huttunen, Riku; Nikkonen, Sami; Sigurðardóttir, Sigríður; Töyräs, Juha; Duce, Brett; Myllymaa, Sami; Arnardottir, Erna Sif; Leppänen, Timo; Islind, Anna Sigridur; Kainulainen, Samu; Korkalainen, Henri. 2024. Journal of sleep research. [First published: 23 October 2024]: 1-13 A1 Journal article (refereed), original research

Temporal and sleep stage‐dependent agreement in manual scoring of respiratory events

Pitkänen, Minna; Pitkänen, Henna; Nath, Rajdeep Kumar; Nikkonen, Sami; Kainulainen, Samu; Korkalainen, Henri; Ólafsdóttir, Kristín Anna; Arnardottir, Erna Sif; Sigurdardottir, Sigridur; Penzel, Thomas; Fanfulla, Francesco; Anttalainen, Ulla; Saaresranta, Tarja; Grote, Ludger; Hedner, Jan; Staats, Richard; Töyräs, Juha; Leppänen, Timo. 2024. Journal of sleep research. [First published: 04 November 2024]: 1-10 A1 Journal article (refereed), original research

Verbal memory is linked to average oxygen saturation during sleep, not the apnea-hypopnea index nor novel hypoxic load variables

Thorisdottir, K; Hrubos-Strøm, H; Karhu, T; Nikkonen, S; Dammen, T; Nordhus, IH; Leppänen, T; Jónsdóttir, MK; Arnardottir, ES. 2024. Sleep medicine. 123: 29-36 A1 Journal article (refereed), original research

Morbid obesity influences the nocturnal electrocardiogram wave and interval durations among suspected sleep apnea patients

Kainulainen, Samu; Suni, Aaron; Lipponen, Jukka A; Kulkas, Antti; Duce, Brett; Korkalainen, Henri; Nikkonen, Sami; Sillanmäki, Saara. 2023. Annals of noninvasive electrocardiology. 2024; 29: A1 Journal article (refereed), original research

Multicentre sleep-stage scoring agreement in the Sleep Revolution project

Nikkonen, Sami; Somaskandhan, Pranavan; Korkalainen, Henri; Kainulainen, Samu; Terrill, Philip I; Gretarsdottir, Heidur; Sigurdardottir, Sigridur; Olafsdottir, Kristin Anna; Islind, Anna Sigridur; oskarsdottir, Maria; Arnardottir, Erna Sif; Leppänen, Timo. 2023. Journal of sleep research. 2024; 33: A1 Journal article (refereed), original research

Multi‐centre arousal scoring agreement in the Sleep Revolution

Pitkänen, Henna; Nikkonen, Sami; Rissanen, Marika; Islind, Anna Sigridur; Gretarsdottir, Heidur; Arnardottir, Erna Sif; Leppänen, Timo; Korkalainen, Henri. 2023. Journal of sleep research. 2024; 33: . e14127 A1 Journal article (refereed), original research

Obstructive Sleep Apnea Patients With Atrial Arrhythmias Suffer From Prolonged Recovery From Desaturations

Rissanen, Marika; Korkalainen, Henri; Duce, Brett; Sillanmaki, Saara; Pitkanen, Henna; Suni, Aaron; Nikkonen, Sami; Kulkas, Antti; Toyras, Juha; Leppanen, Timo; Kainulainen, Samu. 2023. IEEE transactions on biomedical engineering. 70: 2122-2130 A1 Journal article (refereed), original research

Reaction time in psychomotor vigilance task is related to hypoxic load in males with sleep apnea

Pahari, Purbanka; Korkalainen, Henri; Karhu, Tuomas; Arnardottir, Erna Sif; Töyräs, Juha; Leppänen, Timo; Nikkonen, Sami. 2023. Journal of sleep research. 2024; 33: A1 Journal article (refereed), original research

Review and perspective on sleep-disordered breathing research and translation to clinics

Korkalainen, Henri; Kainulainen, Samu; Islind, Anna Sigridur; Óskarsdóttir, María; Strassberger, Christian; Nikkonen, Sami; Töyräs, Juha; Kulkas, Antti; Grote, Ludger; Hedner, Jan; Sund, Reijo; Hrubos-Strom, Harald; Saavedra, Jose M.; Ólafsdóttir, Kristín Anna; Ágústsson, Jón S.; Terrill, Philip I.; McNicholas, Walter T.; Arnardóttir, Erna Sif; Leppänen, Timo. 2023. Sleep medicine reviews. 2024; 73: A2 Review article, Literature review, Systematic review

Towards a Deeper Understanding of Sleep Stages through their Representation in the Latent Space of Variational Autoencoders

Biedebach, Luka; Rusanen, Matias; Pórðarson, Benedikt Hólm; Arnardóttir, Erna Sif; Óskarsdóttir, María; Nikkonen, Sami; Korkalainen, Henri; Myllymaa, Sami; Töyräs, Juha; Kainulainen, Samu; Leppänen, Timo; Islind, Anna Sigridur. Teoksessa: Bui, Tung(toim.) , 2023. Proceedings of the 56th Annual Hawaii International Conference on System Sciences. s. 3111-3120. Hawaii International Conference on System Sciences A4 Conference proceedings

Utilizing Envelope Analysis of a Nasal Pressure Signal for Sleep Apnea Severity Estimation

Varis, Mikke; Karhu, Tuomas; Leppänen, Timo; Nikkonen, Sami. 2023. Diagnostics. 13: A1 Journal article (refereed), original research

A Comparison of Signal Combinations for Deep Learning-Based Simultaneous Sleep Staging and Respiratory Event Detection

Huttunen, Riku; Leppanen, Timo; Duce, Brett; Arnardottir, Erna S.; Nikkonen, Sami; Myllymaa, Sami; Toyras, Juha; Korkalainen, Henri. 2022. IEEE transactions on biomedical engineering. [Date of Publication: 28 November 2022]: 1-12 A1 Journal article (refereed), original research

ABOSA – Freely available automatic blood oxygen saturation signal analysis software: Structure and validation

Karhu, Tuomas; Leppänen, Timo; Töyräs, Juha; Oksenberg, Arie; Myllymaa, Sami; Nikkonen, Sami. 2022. Computer methods and programs in biomedicine. 226: A1 Journal article (refereed), original research

Deep Learning Enables Accurate Automatic Sleep Staging Based on Ambulatory Forehead EEG

Leino, Akseli; Korkalainen, Henri; Kalevo, Laura; Nikkonen, Sami; Kainulainen, Samu; Ryan, Alexander; Duce, Brett; Sipila, Kirsi; Ahlberg, Jari; Sahlman, Johanna; Miettinen, Tomi; Westeren-Punnonen, Susanna; Mervaala, Esa; Toyras, Juha; Myllymaa, Sami; Leppanen, Timo; Myllymaa, Katja. 2022. IEEE access. 10: 26554-26566 A1 Journal article (refereed), original research

Desaturation event scoring criteria affect the perceived severity of nocturnal hypoxic load

Karhu, Tuomas; Leppänen, Timo; Korkalainen, Henri; Myllymaa, Sami; Duce, Brett; Töyräs, Juha; Nikkonen, Sami. 2022. Sleep medicine. 100: 479-486 A1 Journal article (refereed), original research

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project

Sigurdardottir, Fjola D.; Øverby, Caroline Tonje; Nikkonen, Sami; Karhu, Tuomas; Dammen, Toril; Nordhus, Inger Hilde; Thorshov, Thea; Einvik, Gunnar; Kainulainen, Samu; Leppänen, Timo; Arnardottir, Erna Sif; Töyräs, Juha; Omland, Torbjørn; Hrubos‐Strøm, Harald. 2022. Journal of sleep research. 31: . e13581 A1 Journal article (refereed), original research

Obstructive sleep apnea‐related intermittent hypoxaemia is associated with impaired vigilance

Pahari, Purbanka; Korkalainen, Henri; Karhu, Tuomas; Rissanen, Marika; Arnardottir, Erna Sif; Hrubos‐Strøm, Harald; Duce, Brett; Töyräs, Juha; Leppänen, Timo; Nikkonen, Sami. 2022. Journal of sleep research. [First published: 08 December 2022]: A1 Journal article (refereed), original research

Pulse Oximetry: The Working Principle, Signal Formation, and Applications

Leppänen, Timo; Kainulainen, Samu; Korkalainen, Henri; Sillanmäki, Saara; Kulkas, Antti; Töyräs, Juha; Nikkonen, Sami. Teoksessa: Penzel, T; Hornero, R(toim.) , 2022. Advances in the Diagnosis and Treatment of Sleep Apnea. s. 205-218. Springer A3 Book section, Chapters in research books

QTc prolongation is associated with severe desaturations in stroke patients with sleep apnea

Sillanmäki, Saara; Lipponen, Jukka A; Korkalainen, Henri; Kulkas, Antti; Leppänen, Timo; Nikkonen, Sami; Töyräs, Juha; Duce, Brett; Suni, Aaron; Kainulainen, Samu. 2022. Bmc pulmonary medicine. 22: . 204 A1 Journal article (refereed), original research

STAR sleep recording export software for automatic export and anonymization of sleep studies

Nikkonen, Sami; Korkalainen, Henri; Töyräs, Juha; Leppänen, Timo. 2022. Scientific reports. 12: . 15859 A1 Journal article (refereed), original research

The severity and morphology of intermittent hypoxemias are related to impaired daytime alertness

Pahari, P; Korkalainen, H; Karhu, T; Rissanen, M; Arnardottir, ES; Strøm, HH; Duce, B; Töyräs, J; Leppänen, T; Nikkonen, S. 2022. Sleep medicine abstract

Automatic Respiratory Event Scoring in Obstructive Sleep Apnea Using a Long Short-Term Memory Neural Network

Nikkonen, Sami; Korkalainen, Henri; Leino, Akseli; Myllymaa, Sami; Duce, Brett; Leppänen, Timo; Töyräs, Juha. 2021. IEEE journal of biomedical and health informatics. 25: 2917-2927 A1 Journal article (refereed), original research

Diabetes and cardiovascular diseases are associated with the worsening of intermittent hypoxaemia

Karhu, T; Myllymaa, S; Nikkonen, S; Mazzotti, DR; Kulkas, A; Töyräs, J; Leppänen, T. 2021. Journal of sleep research. 2022; 31: e13441 A1 Journal article (refereed), original research

Longer and Deeper Desaturations Are Associated With the Worsening of Mild Sleep Apnea: The Sleep Heart Health Study

Karhu, Tuomas; Myllymaa, Sami; Nikkonen, Sami; Mazzotti, Diego R; Töyräs, Juha; Leppänen, Timo. 2021. Frontiers in neuroscience. 15: 657126 A1 Journal article (refereed), original research

Neural network analysis of nocturnal SpO2 signal enables easy screening of sleep apnea in patients with acute cerebrovascular disease

Leino, Akseli; Nikkonen, Sami; Kainulainen, Samu; Korkalainen, Henri; Töyräs, Juha; Myllymaa, Sami; Leppänen, Timo; Ylä-Herttuala, Salla; Westeren-Punnonen, Susanna; Muraja-Murro, Anu; Jäkälä, Pekka; Mervaala, Esa; Myllymaa, Katja. 2021. Sleep medicine. 79: 71-78 A1 Journal article (refereed), original research

Self-Applied Home Sleep Recordings: The Future of Sleep Medicine

Korkalainen, Henri; Nikkonen, Sami; Kainulainen, Samu; Dwivedi, Amit Krishna; Myllymaa, Sami; Leppänen, Timo; Töyräs, Juha. 2021. Sleep medicine clinics. 16: 545-556 A2 Review article, Literature review, Systematic review

Deep learning enables sleep staging from photoplethysmogram for patients with suspected sleep apnea

Korkalainen, H; Aakko, J; Duce, B; Kainulainen, S; Leino, A; Nikkonen, S; Afara, I O; Myllymaa, S; Töyräs, J; Leppänen, T. 2020. Sleep. 43: zsaa098 A1 Journal article (refereed), original research

Estimating daytime sleepiness with previous night EEG, EOG and EMG spectrograms in patients with suspected sleep apnea using a convolutional neural network

Nikkonen, Sami; Korkalainen, Henri; Kainulainen, Samu; Myllymaa, Sami; Leino, Akseli; Kalevo, Laura; Oksenberg, Arie; Leppänen, Timo; Töyräs, Juha. 2020. Sleep. 43: zsaa106 A1 Journal article (refereed), original research

Longer apneas and hypopneas are associated with greater ultra-short-term HRV in obstructive sleep apnea

Hietakoste, Salla; Korkalainen, Henri; Kainulainen, Samu; Sillanmäki, Saara; Nikkonen, Sami; Myllymaa, Sami; Duce, Brett; Töyräs, Juha; Leppänen, Timo. 2020. Scientific reports. 10: 21556 A1 Journal article (refereed), original research

Novel computational tools for enhanced diagnostics of obstructive sleep apnea

Nikkonen, Sami. 2020. Publications of the University of Eastern Finland. Dissertations in Forestry and Natural Sciences G5 Doctoral dissertation (article)

Power spectral densities of nocturnal pulse oximetry signals differ in OSA patients with and without daytime sleepiness

Kainulainen, Samu; Töyräs, Juha; Oksenberg, Arie; Korkalainen, Henri; Afara, Isaac O; Leino, Akseli; Kalevo, Laura; Nikkonen, Sami; Gadoth, Natan; Kulkas, Antti; Myllymaa, Sami; Leppänen, Timo. 2020. Sleep medicine. 73: 231-237 A1 Journal article (refereed), original research

Accurate Deep Learning-Based Sleep Staging in a Clinical Population with Suspected Obstructive Sleep Apnea

Korkalainen, Henri; Aakko, Juhani; Nikkonen, Sami; Kainulainen, Samu; Leino, Akseli; Duce, Brett; Afara, Isaac Oluwaseun; Myllymaa, Sami; Töyräs, Juha; Leppänen, Timo. 2019. IEEE journal of biomedical and health informatics. 24: 2073-2081 A1 Journal article (refereed), original research

Artificial neural network analysis of the oxygen saturation signal enables accurate diagnostics of sleep apnea

Nikkonen, S; Afara, IO; Leppänen, T; Töyräs, J. 2019. Scientific reports. 9: 13200 A1 Journal article (refereed), original research

Intra-night variation in apnea-hypopnea index affects diagnostics and prognostics of obstructive sleep apnea

Nikkonen, S; Töyräs, J; Mervaala, E; Myllymaa, S; Terrill, P; Leppänen, T. 2019. Sleep and breathing. 2020; 24: 379-386 A1 Journal article (refereed), original research

Mortality-risk-based apnea-hypopnea index thresholds for diagnostics of obstructive sleep apnea

Korkalainen, H; Töyräs, J; Nikkonen, S; Leppänen, T. 2019. Journal of sleep research. 28: e12855 A1 Journal article (refereed), original research

Required CPAP usage time to normalize AHI in obstructive sleep apnea patients: a simulation study

Kulkas, Antti; Leppänen, Timo; Nikkonen, Sami; Oksenberg, Arie; Duce, Brett; Mervaala, Esa; Töyräs, Juha. 2018. Physiological measurement. 39: 115009 A1 Journal article (refereed), original research

Simulation of Required CPAP Usage to Normalize AHI in Obstructive Sleep Apnea Patients

Kulkas, Antti; Nikkonen, Sami; Töyräs, Juha; Mervaala, Esa; Leppänen, Timo. Teoksessa: Lhotska, L; Sukupova, L; Lackovic, I; Ibbott, G(toim.) , 2018. World Congress on Medical Physics and Biomedical Engineering 2018, June 3-8, 2018, Prague, Czech Republic (Vol.2). s. 129-132. Springer A4 Conference proceedings

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A comparative analysis of unsupervised machine‐learning methods in PSG‐related phenotyping

Excessive daytime sleepiness is associated with relative delta frequency power among patients with mild OSA

Interhemispheric differences of electroencephalography signal characteristics in different sleep stages

Prolonged lung-to-finger circulation time indicates an increased risk of intermittent hypoxaemia in sleep apnoea patients

Respiratory event index underestimates severity of sleep apnea compared to apnea-hypopnea index

Retrospective validation of automatic sleep analysis with grey areas model for human‐in‐the‐loop scoring approach

Temporal and sleep stage‐dependent agreement in manual scoring of respiratory events

Verbal memory is linked to average oxygen saturation during sleep, not the apnea-hypopnea index nor novel hypoxic load variables

Morbid obesity influences the nocturnal electrocardiogram wave and interval durations among suspected sleep apnea patients

Multicentre sleep-stage scoring agreement in the Sleep Revolution project

Multi‐centre arousal scoring agreement in the Sleep Revolution

Obstructive Sleep Apnea Patients With Atrial Arrhythmias Suffer From Prolonged Recovery From Desaturations

Reaction time in psychomotor vigilance task is related to hypoxic load in males with sleep apnea

Review and perspective on sleep-disordered breathing research and translation to clinics

Towards a Deeper Understanding of Sleep Stages through their Representation in the Latent Space of Variational Autoencoders

Utilizing Envelope Analysis of a Nasal Pressure Signal for Sleep Apnea Severity Estimation

A Comparison of Signal Combinations for Deep Learning-Based Simultaneous Sleep Staging and Respiratory Event Detection

ABOSA – Freely available automatic blood oxygen saturation signal analysis software: Structure and validation

Deep Learning Enables Accurate Automatic Sleep Staging Based on Ambulatory Forehead EEG

Desaturation event scoring criteria affect the perceived severity of nocturnal hypoxic load

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project

Obstructive sleep apnea‐related intermittent hypoxaemia is associated with impaired vigilance

Pulse Oximetry: The Working Principle, Signal Formation, and Applications

QTc prolongation is associated with severe desaturations in stroke patients with sleep apnea

STAR sleep recording export software for automatic export and anonymization of sleep studies

The severity and morphology of intermittent hypoxemias are related to impaired daytime alertness

Automatic Respiratory Event Scoring in Obstructive Sleep Apnea Using a Long Short-Term Memory Neural Network

Diabetes and cardiovascular diseases are associated with the worsening of intermittent hypoxaemia

Longer and Deeper Desaturations Are Associated With the Worsening of Mild Sleep Apnea: The Sleep Heart Health Study

Neural network analysis of nocturnal SpO2 signal enables easy screening of sleep apnea in patients with acute cerebrovascular disease

Self-Applied Home Sleep Recordings: The Future of Sleep Medicine

Deep learning enables sleep staging from photoplethysmogram for patients with suspected sleep apnea

Estimating daytime sleepiness with previous night EEG, EOG and EMG spectrograms in patients with suspected sleep apnea using a convolutional neural network

Longer apneas and hypopneas are associated with greater ultra-short-term HRV in obstructive sleep apnea

Novel computational tools for enhanced diagnostics of obstructive sleep apnea

Power spectral densities of nocturnal pulse oximetry signals differ in OSA patients with and without daytime sleepiness

Accurate Deep Learning-Based Sleep Staging in a Clinical Population with Suspected Obstructive Sleep Apnea

Artificial neural network analysis of the oxygen saturation signal enables accurate diagnostics of sleep apnea

Intra-night variation in apnea-hypopnea index affects diagnostics and prognostics of obstructive sleep apnea

Mortality-risk-based apnea-hypopnea index thresholds for diagnostics of obstructive sleep apnea

Required CPAP usage time to normalize AHI in obstructive sleep apnea patients: a simulation study

Simulation of Required CPAP Usage to Normalize AHI in Obstructive Sleep Apnea Patients