As Melbourne wakes up bleary-eyed from an art-filled all-nighter, Victoria Police says it's satisfied with crowd behaviour during White Night.

The state government and White Night event organisers both estimated attendance at the city-wide dusk until dawn event reached 600,000, slightly more than last year.

Events included a swing dance marathon in Collins Street, pop up cinema in Lonsdale Street and colourful projections on the State Library and other landmarks.

As of 5.15am on Sunday, police had arrested 21 people and charged them with alcohol, drug, assault, damage and weapon-related offences.

This included officers having to use pepper spray to break up a melee in Federation Square just after 2am.

Meanwhile, paramedics were kept busy at an electronic music festival at the Sidney Myer Music Bowl where more than 30 people were treated for drug overdoses, and more than 20 went to hospital, mostly in a critical condition.

Ambulance Victoria treated 46 people at White Night events, eight of which were drug overdoses, a spokesman said.

Homeless advocates camped at Victoria's State Library to protest against a proposed rough sleeping ban in front of crowds pouring in to Melbourne for the annual event.

Placards read: "No homless ban", "Public housing for the homeless" and "People are not rubbish you can't sweep them off the streets".

White Night Melbourne was directed by Melbourne-born choreographer and producer David Atkins, who was the creative force behind the Sydney Olympic opening and closing ceremonies and the 2010 Vancouver Winter Olympics.

The Victorian regional town of Ballarat will host its first White Night in two weeks' time.