Traditionally, various Hindustani (North Indian) ragas have been performed at specific times of day, such as dawn, dusk, midday, and evening. Human physiology also exhibits common circadian patterns, with reduced arousal at night, rising during the morning, culminating in peak arousal, and then declining arousal towards the end of the day. This raises the question of how and whether the musical features of ragas for each time of day are related to these circadian patterns of arousal. We formally examined associations between traditionally designated time-of-day classifications and musical features from 65 Hindustani raga performances. Our results showed that only pitch-related features are predictive of time-of-day classifications. Surprisingly, non-pitch factors known to correlate with arousal, such as tempo, did not covary with raga time-of-day practices. In general, the results are consistent with rules for North Indian raga performances described by Vishnu Narayan Bhatkhande (1860–1936) that emphasize the presence or prevalence of particular tones in the raga. The results point to a combination of enculturated and embodied influences in conveying musical arousal. Specifically, they suggest that while time-of-day-related raga listening practices may have been initially influenced by embodied processes, they have ultimately been reshaped by pitch-related cultural norms.
