Ashunya Shayan Vrat or Shoonya Sayan Vratam is the festival observed during Shravan month. Ashunya Sayana Vrata is dedicated to Lord Vishnu and Goddess Lakshmi. Ashunya Shayan Vrat is observed on Shravan Krishna Paksha Dwitiya or Vidiya.
In 2016, Ashoonya Shayan Vrat date as per North Indian calendar is July 21. As per Andhra Pradesh, Telangana, Karnataka, Maharashtra and Gujarat calendars, date of Asoonya Shayan Vratam is August 20.
Vishnu Shayanotsav – Main ritual during Ashunya Shayan Vrata:
During the period of Shravan or all the four holy months (Chaturmas), Sri Maha Vishnu and Lakshmi take rest on Aadiseshu upon the Milk Ocean (Ksheer Sagar). The main ritual during Ashunya Shayan Vrata includes Vishnu Shayanotsav. Devotees keep fast during the day time on the day of Vrata and perform Shayanotsavam to Lord Vishnu.
On the occasion of Vrata, Lord Vishnu and Goddess Laxmi are worshipped with Shodashopachar (16 types of puja rituals). Ashunya Shayan Vrata is observed by married couple for marital bliss and welfare of the family.
In some regions in India, Ashoonya Sayana Vratam is observed on the second day after the Krishna Paksha Purnima in Kartik month. Legend or story of Ashunya Shayan Vrat is mentioned in Narada Purana. It explains how a man struggled with starvation and hunger, was born as a great successful King in his next birth.