Sleep Research Centre

The Sleep Research Centre is a multidisciplinary research group, which is reflected in the topics of the academic dissertations. There are several ongoing research projects in co-operation with other Finnish and international research groups. 

The main research interests at the centre are interactions of sleep-disordered breathing and cardiovascular and metabolic function, special emphasis on nocturnal transcutaneous carbon dioxide profile, and menopause, sleep and breathing. 

The Sleep Research Centre also organises Sleep School once a month during the academic year under the umbrella of the Postgraduate Education Unit (PGE). 

The history of the Sleep Research Centre at the Department of Physiology dates back to the 1960’s when Associate Professor Pentti Valleala carried out sleep research in animals. Sleep research in humans started in the 1970’s. In 1979, Jukka Alihanka developed the static-charge sensitive bed (SCSB). The SCSB method was further developed by Olli Polo and implemented in the diagnosis of obstructive and central sleep apnoea, partial upper airway obstruction during sleep as well as in periodic leg movements. In Finland, sleep apnoea was mostly diagnosed with the help of the SCSB until the end of the 20th century. Since 2017, Sleep Research Centre has been part of the Department of Pulmonary Diseases and Clinical Allergology. 

Contact Information

Address: ​Sleep Research Unit, University of Turku, Lemminkäisenkatu 3b, FI-20520 TURKU


Professor Tarja Saaresranta

Research Coordinator: Marjo Sunnari


Olli Polo
Päivi Polo
Jenni Aittokallio
Ulla Anttalainen
Nea Kalleinen
Salla Lamusuo
Arho Virkki
Irina Virtanen

Doctoral Candidates 

Miia Aro
Laura Lampio
Silja Runsten
Karri Utriainen

Research Projects

The Sleep Research Centre promotes co-operation and dialogue across disciplinary and institutional boundaries within the field of sleep research. Having its roots in basic physiology, the Sleep Research Centre aims at unfolding physiological mechanisms behind normal and disturbed sleep and disseminating new data in the field of sleep medicine for the benefit of medical students, health care professionals, scientists and the society. 


Menopause offers a useful model to study the interactions between breathing and vascular disease. Both sleep-disordered breathing and vascular diseases increase after menopause but the effects of ageing and menopause per se are not fully understood. Premenopausal women at the age of 46 are followed up for ten years and studies will be carried out also in a cross-sectional cohort of 56-year old women.

The overall aim of the study is to clarify the interactions of nocturnal breathing abnormalities and metabolic dysfunction in middle-aged women.

The specific aims of the 5- and 10-year follow-up study are to test the effect of menopause on

  • endothelial function and subclinical atherosclerosis 
  • sleep-disordered breathing
  • sleep structure and quality, and
  • daytime sleepiness

with special emphasis on nocturnal transcutaneous carbon dioxide tension profile.

Length: 2001- 

Principal Investigator: Professor Tarja Saaresranta


ESADA (European Sleep  Apnea Database) is an observational prospective real-world cohort study in collaboration between European sleep centers. 

The overall aim of the ESADA project is:

  • to build the largest existing database of patients with sleep and breathing disorders. 
  • to collect patient information from a network of European sleep centers.
  • to execute cross-sectional, prospective, interventional or long-term follow-up studies based on information in the data base.

Specific study targets and objectives

Primary objective:

  • to generate cross sectional data on anthropometrics, sleepiness measures and comorbidity in European patients with various degree of OSA severity.

Secondary objectives:

  • to measure the incidence of cardiovascular diseases.
  • to prospectively explore the cardiovascular and overall mortality in OSA and its relation to OSA severity and cardiovascular risk factors.
  • to explore the effect of different OSA treatment modalities on hemodynamic and metabolic parameters as well as on cardiovascular morbidity, metabolic disorder and sleepiness. 

Tertiary objectives: 

  • to explore the dose-response relationship between OSA severity and hypertension, hyperglycemia, cardiovascular morbidity, metabolic disorder and sleepiness.
  • to assess the effect of age, gender, domicile as well as cardiovascular and metabolic comorbidity on cardiovascular endpoints in sleep apnea patients 
  • to assess the value of various sleep laboratory procedures in terms of diagnostic and treatment routines on outcome in sleep apnea patients.
  • to assess the safety, tolerability and compliance with long-term CPAP treatment, oral devices and surgery (safety and tolerability) 

European sleep laboratory clinical process evaluation 

  • to assess the regional differences across sleep laboratories in Europe regarding patient populations, treatment allocations, diagnostic work up, as well as adherence to therapy.
  • to transfer know-how and to unify procedures as well as to generate minimum standards between different European sleep laboratories by the use of a standardized data acquisition procedure.
  • to generate a data base to be used for future health economical assessments in sleep apnea patients in relation to the various national health care systems. 

Substudy protocols to be generated from the joint database 

  • to create a network of scientifically active sleepcentres and a joint database to be used for specific patient recruitment in collaborative studies.

Recruitment, analyses and reporting ongoing.

Duration of the study: 2007- 

Principal Investigator in Finland: Professor Tarja Saaresranta

Sleep Revolution

Revolution of sleep diagnostics and personalized health care based on digital diagnostics and therapeutics with health data integration.

Sleep Revolution is a multidisciplinary and international research and development project funded by the Horizon 2020 Framework Programme for Health, Demographic Change and Wellbeing, and jointly coordinated by the University of Reykjavik and the University of Eastern Finland.

Obstructive sleep apnea (OSA) is associated with various negative health consequences including increased risk of heart disease, hypertension and daytime sleepiness causing road accidents. The economic burden of OSA is rising as almost 1 billion people worldwide are estimated to have OSA. The current diagnostic metric, however, relates poorly to these symptoms and comorbidities. It merely measures the frequency of breathing cessations without assessing OSA severity in any other physiologically relevant way. Furthermore, the clinical methods for analyzing PSG signals are outdated, expensive and laborious. Due to this, the majority of OSA patients remain without diagnosis or have an inaccurate diagnosis leading to sub-optimal treatment. Thus, it is evident that more personalized diagnostics are required including predictive and preventive health care and patient participation. The SLEEP REVOLUTION aims to develop machine learning techniques to better estimate OSA severity and treatment needs to improve health outcomes and quality of life. These techniques are implemented to high-end wearables developed in this project to alleviate the costs and increase the availability of PSGs. Finally, we aim to design a digital platform that functions as a bridge between researchers, patients and healthcare professionals. We will achieve these ambitious goals throughout extensive collaboration between sleep specialists, computer scientists and industry partners. The collaboration network consists of over 30 sleep centers working together to provide the needed retrospective data (over 10.000 sleep studies). The multi-center prospective trials involve experts and end-users to assess and validate the new SLEEP REVOLUTION diagnostic algorithms, wearables and platforms. With the commitment of the European Sleep Research Society and Assembly of National Sleep Societies (over 8000 members), we have the unique possibility to create new standardized guidelines for sleep medicine in the EU.

sleep revolution kaavio


  • Transform current diagnostic methods for sleep-disordered breathing (SDB)
  • Bring advanced sleep diagnostics from hospital into patient’s home
  • Promote participatory health care with technological solutions
  • Develop different personalized treatment options for SDB

Duration of the study: Started March 1, 2021

Principal investigator at the University of Turku: Professor Tarja Saaresranta

Principal investigator at the Turku University Hospital: Adjunct professor Ulla Anttalainen

Interaction of Sleep, Diurnal Eating Pattern, Gut Microbiota, and Obesity

The data are fragmented and studies are focusing on interactions of sleep and obesity, eating pattern and obesity, or gut microbiota and obesity, but not the cross-talk of all these factors in the same individual or population. Therefore, we need a multifactorial approach to get a more deep insight on the obesity and weight regulation. Further, novel cost-effective tools to advance lifestyle changes are needed. Emerging evidence suggests that novel countermeasures, such as modulation of the timing of food intake, may be effective strategies in weight control and prevention of obesity. 


  • to provide scientific basis for the relationship between subjective sleep quality, diurnal eating pattern, gut microbiome, and obesity
  • to develop and test a pragmatic, cost-effective new tool to advance lifestyle changes using E-health approach
  • to compare differences in subjective sleep quality, diurnal eating pattern and gut microbiome at baseline
  • to compare changes induced by the E-health intervention among the three study groups and participants with different work schedules


  • Three groups of participants will be recruited via newspaper announcements, social media, and the database of the Turku University Hospital: community dwelling 18 – 65 year old adults 1) with BMI 18.5 - 30 kg/m2 (n = 40, M:F = 1:1), 2) BMI > 30 kg/m2 (n = 40, M:F = 1:1), and 3) OSAS patients with BMI > 30 kg/m2 using nasal continuous positive airway pressure (CPAP) treatment on an average > 4 h/d (n = 40, M:F = 1:1).
  • Exclusion criteria: antimicrobial treatment within 3 months prior the baseline visit, inflammatory bowel diseases.

Course of the Study

  • Baseline phase (3 weeks)
  • Intervention phase (16 weeks)
  • Follow-up phase (24 months) identifier (NCT number): NCT04850391

Duration of the study: Recruitment will start in August 2021.

Principal investigator: Professor Tarja Saaresranta