Our Gemara on Amud Beis discusses the halachic phenomenon that tefilin are not worn at night nor on Shabbos.

Dover Tzedek, Kuntres Ner HaMitzvos (1), offers a beautiful psychological explanation that unites these two laws. There are two dimensions to mitzvos, represented by positive action commandments and negative commandments of restraint. Symbolically—and practically, especially in a pre-industrial society—nighttime is a period of passivity. One withdraws, hunkers down, and remains safe and contained. Tefilin represent the opposite of passivity. They are an active externalization of accepting the yoke of Heaven upon one’s head and heart (Megillah 16b). Activity belongs to the daytime. Similarly, Shabbos is a time for reflection and inner work, not for outward action, therefore tefiiin are not worn..

On a deeper level, avodas Hashem is not monolithic. There are times when reflection alone is insufficient and action is required. Conversely, there are times when action is excessive and quiet contemplation is necessary. God designed both the world and the Torah according to this rhythm. As the Zohar states, Hashem looked into the Torah and created the world (Zohar II:161a). Our cycles of sleep and wakefulness, night and day, reflect a deeper truth: there is inherent value in alternating between action and reflection.