Comparison of deep transfer learning algorithms and transferability measures for wearable sleep staging

Abstract

Background: Obtaining medical data using wearable sensors is a potential replacement for in-hospital monitoring, but the lack of data for such sensors poses a challenge for development. One solution is using in-hospital recordings to boost performance via transfer learning. While there are many possible transfer learning algorithms, few have been tested in the domain of EEG-based sleep staging. Furthermore, there are few ways for determining which transfer learning method will work best besides exhaustive testing. Measures of transferability do exist, but are typically used for selection of pre-trained models rather than algorithms and few have been tested on medical signals. We tested several supervised transfer learning algorithms on a sleep staging task using a single channel of EEG (AF7-Fpz) captured from an in-home commercial system.

Results: Two neural networks-one bespoke and another state-of-art open-source architecture-were pre-trained on one of six source datasets comprising 11,561 subjects undergoing clinical polysomnograms (PSGs), then re-trained on a target dataset of 75 full-night recordings from 24 subjects. Several transferability measures were then tested to determine which is most effective for assessing performance on unseen target data. Performance on the target dataset was improved using transfer learning, with re-training the head layers being the most effective in the majority of cases (up to 63.9% of cases). Transferability measures generally provided significant correlations with accuracy (up to [Formula: see text]).

Conclusion: Re-training the head layers provided the largest performance boost. Transferability measures are useful indicators of transfer learning effectiveness.

Keywords: Domain adaptation; EEG; Machine learning; Sleep staging; Transfer learning; Wearable medical devices.

Fig. 1

Architecture of base model

Fig. 2

Architecture of open-source model, DeepSleepNet [43]. Image courtesy of Supratak et al. [43]