Bengal's Diwali is Kali Puja; Goddess Kali worshipped through the night

Kali Puja, also called Shyama Puja, is the worship of Goddess Kali on the midnight of Kartika Amavasya, the same night as Diwali, and is the main festival of this night in West Bengal, Odisha, Assam, Tripura and Mithila. Kali, the fierce dark form of the Divine Mother, is the power of time (Kala) that destroys ego, ignorance and evil. The Devi Mahatmya describes how she sprang from Durga's forehead to slay Chanda and Munda and drank the blood of Raktabija so that no new demons could arise. Frenzied with victory, she could not be stopped until Shiva lay beneath her feet, and on seeing him she bit her tongue in shame — the image seen in Bengal's pandals. The worship, popularised in the 18th century by Raja Krishnachandra of Nadia and by sages such as Ramprasad Sen and Sri Ramakrishna at Dakshineswar, is done through the night with red hibiscus, 108 lamps, sweets, lentils, rice, fish in some homes, and in tantric tradition animal sacrifice (now largely symbolic). Homes light lamps and candles, and the evening before, on Bhoot Chaturdashi, fourteen lamps are lit and fourteen leafy greens eaten to ward off spirits.

Devotees fast until the night puja and take bhog after.