The observers of vrata on Ekadashis sometimes prefer to fast, and/or fast without drinking water, and/or spend sleepless night. Sometimes devotees chant and praise the Lord always and keep awake the whole night.

"Once a year in the early summer there is a special Ekadasi known as the Pandava-nirjala Ekadasi or Bhima Ekadasi. Back in the days of the Mahabharata, five thousand years ago, Arjuna's elder brother Bhima had great difficulty fasting. (In those days everyone would fast completely from all food and water.) So he was given permission by the sage Vyasadeva to observe the full Ekadasi fast only once a year. In the Krsna consciousness movement many devotees are accustomed to following this Bhima Ekadasi, refraining from all food and water, to compensate for any discrepancies in their observance o...