In Jainism, "Ratri Vihar" refers to the practice of traveling or moving about at night. According to Jain teachings, night travel is generally discouraged for both monks and laypersons (śrāvakas).

Reasons:

• Non-violence (Ahimsa): Many small living beings, such as insects, come out at night and are difficult to see. Traveling at night increases the risk of unintentionally harming them, which goes against the core Jain principle of ahimsa.
• Spiritual discipline: Jain monks and nuns (sādhus and sādhvīs) are especially instructed to settle down before sunset and not travel until after sunrise, emphasizing carefulness (samiti) and vigilance (apramāda).

Exceptions:

• In extreme or unavoidable circumstances (such as danger to life), exceptions may be considered, but generally, the practice is to avoid "ratri vihar."

References:

• Jain scriptures like the Ācāranga Sūtra and various mūla sūtras lay down guidelines for monks and nuns regarding movement at night.
• Laypersons are also encouraged to avoid unnecessary travel after sunset.

Summary: According to Jainism, "ratri vihar" is generally not considered right and is avoided to uphold the principle of non-violence and care towards all forms of life.