In Jainism, Vāyukāyik jīv means air-bodied beings – very subtle living beings whose body is made of air (vāyu).

First, an important point:

• As a dravya (substance / class of jīv), Vāyukāyik is the same in day and night.

The type of soul does not change with time. Difference is only in their activity, quantity, and our likelihood of harming them.

How they differ practically in day and night

1. Movement and disturbance

- In the daytime, we can see better, so: - We move more carefully. - We can avoid many visible beings (like flying insects). - Work like sweeping, cleaning, cooking can be done with more attention. - At night, due to darkness: - We walk, work, open/close doors, etc. with less visibility. - This causes more disturbance in air, so more harm to Vāyukāyik jīv (and also to small mobile beings like insects).

1. Around light and fire at night

- At night, when a lamp, tube-light, mobile light, or fire is used: - Many minute insects and air-bodied beings gather near the flame/light. - Blowing air, waving hands, moving near those lights, lighting/extinguishing the flame etc. causes more hiṁsā to these subtle beings. - In the day, natural sunlight spreads everywhere, so this concentration of beings around one source is less.

1. Rule of not eating at night

- Traditional Jain āchārs say “do not eat after sunset”. - One major reason: In darkness, even with a lamp, very tiny beings in air and on food cannot be seen, so: - More Vāyukāyik hiṁsā (disturbance of air-bodied beings). - More micro-insects (trasa jīv) mixing with food. - So, the risk of violence is much higher at night than in the day.

1. Sūkṣma (subtle) hiṁsā count

- Every time we: - Open/close windows - Use fans, AC, blow air from mouth - Shake clothes, bed-sheets, etc. we disturb Vāyukāyik jīv. - These actions are naturally more careless at night, increasing aprāmatt (unmindful) hiṁsā.

Summary

• Ontologically:

Vāyukāyik jīv are exactly the same type day and night.

• Practically (vyavahār):

- At night, due to darkness, artificial light, and careless movement, we usually cause more hiṁsā to air-bodied (and other subtle) beings than in the day. - Therefore, Jain discipline (no food at night, minimize movement, no unnecessary work) is taught to reduce violence toward such jīv.

So the “difference” is not in the jīv themselves, but in our visibility, activity, and the amount of hiṁsā we end up doing to Vāyukāyik jīv in day vs night.