Obstructive sleep apnea (OSA) does not necessarily look the same every night. Sleep position, sleep stage, alcohol consumption, nasal congestion and other physiological or behavioral factors can influence breathing during sleep. As a result, the severity of sleep-disordered breathing can vary from one night to the next1, increasing the interest in multi-night sleep testing. That is, capturing the variability across nights by collecting sleep and respiratory data across more than one night to provide a broader view of a patient’s sleep-disordered breathing.
For appropriate patients, multi-night home sleep apnea testing (HSAT) offers an opportunity to observe respiratory patterns over time while patients sleep in their usual environment. But collecting additional nights also creates practical questions around patient setup, signal quality, data volume, scoring and clinical interpretation.
What are the benefits of multi-night sleep testing?
One of the primary potential benefits is the ability to account for night-to-night variability in OSA.
In a study of 10,340 adults who completed three consecutive nights of Type III home sleep testing, Punjabi and colleagues found that OSA severity classification could vary depending on which night was evaluated. The effect was particularly important among people with mild or moderate OSA.2
Larger longitudinal research has reinforced that finding. Lechat and colleagues analyzed more than 11.6 million nights of home recordings from 67,278 people and found substantial variation in OSA severity across nights.3 Together, these findings suggest that repeated measurement can provide information that may not always be apparent from a single snapshot.
Multi-night testing can also allow patients to be studied in their normal sleeping environment over several nights rather than relying on one laboratory night. That may help capture differences related to sleep position, sleep architecture and other factors that naturally change from night to night.
Importantly, this does not mean every patient requires multiple nights of testing. The number of nights needed, and the clinical value of additional measurements, will depend on the patient, the diagnostic question, and the testing methodology.
Reliable respiratory signals matter across every night
Collecting more nights is useful only when the physiological signals being recorded remain meaningful.
For home sleep apnea testing, respiratory signals such as airflow, respiratory effort and oxygen saturation provide the foundation for identifying sleep-disordered breathing. When testing is repeated across several nights, comfortable sensor application and reliable signal acquisition become especially important.
The Nox T3s™ home sleep testing system uses dual respiratory inductance plethysmography (RIP) belts to measure thoracic and abdominal movement alongside other respiratory signals. The system is designed to support multiple-night recordings, including extended battery performance for multi-night studies.4
Recent research has also expanded what can be learned from RIP signals. Finnsson et al. demonstrated that, with appropriate calibration and processing, dual RIP can quantify changes in ventilation relative to eupneic breathing and support measures including respiratory event depth and ventilatory burden.5
What are the barriers to multi-night sleep testing?
More nights also mean more data to manage.
Each additional recording must be acquired successfully, transferred, reviewed and interpreted. Without efficient workflows, the benefit of additional nights can be offset by greater scoring and administrative workload.
Patient education is another important consideration. When patients apply sensors themselves at home, clear instructions and simple, repeatable setup become increasingly important as the number of nights increases.
There is also no single universally appropriate number of nights for every clinical situation. Research shows that greater numbers of observations can increase confidence in estimates of an individual’s typical OSA severity, but the practical balance between diagnostic information, patient burden and clinical resources remains an important consideration.2,3
Reimbursement and local testing requirements may also influence whether multi-night studies are practical and should be evaluated within each healthcare setting.
Technology is changing what is practical at home
What is possible with multi-night sleep testing today changes along with technology development, including the increasing ability to extract more information from HSAT.
For example, research published in 2025 demonstrated that BodySleep 2.0, an AI algorithm developed by Nox, can identify sleep states and arousals using RIP signals, with total sleep time showing strong agreement with reference scoring.6 These types of analysis have not been possible previously with HSAT.
The goal of multi-night testing is not simply to collect more data. It is to collect useful physiological information across time in a way that remains practical for patients and clinicians.
As home sleep testing continues to evolve, multi-night recordings offer an increasingly important opportunity to understand how sleep-disordered breathing changes beyond a single night — and to determine when that additional information can support clinical decision-making.
References
- Stöberl AS, Schwarz EI, Haile SR, et al. Night-to-night variability of obstructive sleep apnea. J Sleep Res. 2017 Dec;26(6):782-8.
- Punjabi, N. M., Patil, S., Crainiceanu, C., & Aurora, R. N. (2020). Variability and misclassification of sleep apnea severity based on multi-night testing. Chest, 158(1), 365–373. https://doi.org/10.1016/j.chest.2020.01.039
- Lechat, B., Naik, G., Reynolds, A., Aishah, A., Scott, H., Loffler, K. A., Vakulin, A., Escourrou, P., McEvoy, R. D., Adams, R. J., Catcheside, P. G., & Eckert, D. J. (2022). Multinight prevalence, variability, and diagnostic misclassification of obstructive sleep apnea. American Journal of Respiratory and Critical Care Medicine, 205(5), 563–569. https://doi.org/10.1164/rccm.202107-1761OC
- Nox Medical. (n.d.). Nox T3s™ HST. https://noxmedical.com/noxt3s/
- Finnsson, E., Arnardottir, E., Montazeri, K., Keenan, B. T., Schwab, R. J., Gislason, T., Pack, A. I., Wellman, A., Islind, A. S., Ágústsson, J. S., & Sands, S. A. (2026). Respiratory inductance plethysmography to quantify changes in ventilation in obstructive sleep apnea. IEEE Transactions on Biomedical Engineering, 73(5), 1943–1952. https://doi.org/10.1109/TBME.2025.3618403
- Finnsson, E., Erlingsson, E., Hlynsson, H. D., Valsdóttir, V., Sigmarsdottir, T. B., Arnardóttir, E., Sands, S. A., Jónsson, S. Æ., Islind, A. S., & Ágústsson, J. S. (2025). Detecting arousals and sleep from respiratory inductance plethysmography. Sleep and Breathing, 29, Article 155. https://doi.org/10.1007/s11325-025-03325-z
Topic: Industry News
