Introduction: Accurate sleep-stage classification plays a critical role in understanding sleep physiology and diagnosing related disorders. Electroencephalogram (EEG) signals provide rich temporal and spectral information, but their inherent complexity and variability pose challenges for automated analysis. Recent advances in deep learning have enabled the extraction of discriminative features, thereby improving classification performance. Methods: EEG signals were acquired, segmented, labelled, and processed to extract features, including Power Spectral Density (PSD), Petrosian Fractal Dimension (PFD), Hjorth parameters, the Hurst exponent, and Detrended Fluctuation Analysis (DFA). Pre-processing involved class balancing, normalization, and band-pass filtering. A parallel architecture integrating Long Short-Term Memory (LSTM) networks and Convolutional Neural Networks (CNNs) was designed to capture temporal dependencies and spatial representations simultaneously. Early stopping and adaptive learning-rate scheduling were employed to ensure stable training and to prevent over-fitting. Results: Evaluation metrics included accuracy curves, confusion matrices, ROC curves, precision– recall plots, and calibration curves. The model demonstrated strong precision, recall, and F1-scores, particularly excelling in detecting Class 2 stages. Statistical analyses using chisquare tests, Kolmogorov–Smirnov statistics, and contingency analysis confirmed calibration reliability and discriminative capability. Discussion: The proposed framework effectively integrates handcrafted EEG features with deep-learning-based modelling to address both temporal and spatial signal complexities. While the model achieved robust performance across sleep stages, challenges persisted in classifying minority stages, highlighting the need for further refinement of data-augmentation and classbalancing strategies. Conclusion: The study presents a reliable and interpretable sleep-stage classification pipeline that combines signal processing with deep learning, underscoring its potential for clinical applications and the importance of improving minority-class detection.
Basak et al. (Wed,) studied this question.