Jaya Ekadasi is observed during the waxing phase of the moon (Shukla Paksha) in the month of January/February. In 2015, the date of Jaya Ekadashi is January 31. It is also observed as Bhishma Ekadashi and Bhoumi Ekadasi by various Hindu communities. It is believed that observing Jaya Ekadashi will help in getting rid of remorse attached to sins committed and it also leads to liberation (Moksha).
The importance of Jaya Ekadashi was narrated to Yudhishtira by Lord Krishna and is found in the Padma Purana and the Bhavisyothara Purana
Fasting on Jaya Ekadashi is considered highly beneficial. Some staunch Vishnu devotees also do not sleep during the night. All the normal rules associated with Ekadashi fasting is followed.
source – http://www.hindu-blog.com/2009/01/jaya-ekadashi.html