In Jain tradition, many communities follow restrictions during menstruation mainly as a discipline of ritual and bodily purity, and also to follow the principle of ahimsa with extra care.

Common explanations are:

• Menstruation is considered a time of bodily change and weakness, so women are often asked to rest.
• Some customs treat the body during this time as less suitable for temple worship, touching idols, or handling sacred items.
• In certain traditions, it is also seen as a way to avoid unintentional harm to subtle living beings through increased bodily activity, contact, or ritual handling.

Important points:

• These practices are traditional customs, and they can vary by sect, region, and family.
• Jain scripture and practice are followed differently in Digambar and Shwetambar traditions, and local customs may be stricter or more relaxed.
• The core Jain value is non-violence and self-discipline, not disrespect toward women.

So, in simple words: women are often asked not to touch certain things during menstruation because of traditional ideas of ritual purity, rest, and careful observance of ahimsa.