Answer

In Jain Dharma, if you are observing the practice of not eating at night — commonly called Chauvihar — then lassi should not be taken at night.

Explanation

Lassi is made from curd/yogurt and is considered a food-like drink. In Jain discipline, night eating is avoided because:

• There is greater possibility of harming tiny living beings after sunset.
• Food and drinks may contain subtle organisms that are harder to see at night.
• It supports self-control and reduces attachment to taste.

If someone is doing:

• Chauvihar: no food or water after sunset — lassi is not allowed.
• Tivihar: no food after sunset, but water may be allowed — lassi is still not allowed, because it is not plain water.
• Duvihar: certain limited items may be permitted depending on tradition and guidance — one should follow the instruction of their Guru or family tradition.

Spiritual Understanding

The purpose of avoiding food at night is not only a rule, but a practice of ahimsa, restraint, and awareness. Lassi, being nourishing and taste-based, is generally treated as food rather than simple water.

Takeaway

If you do not eat at night according to Jain practice, then you should avoid drinking lassi at night. Plain boiled and cooled water may be taken only if your observance permits it, such as in Tivihar.