A 23-year-old woman is fighting for her life in a Sydney hospital after she overdosed on drugs at the music festival Field Day, held on New Year's Day.

A St Vincent's Hospital spokesperson told Fairfax Media the woman was admitted during a "very busy night" and remained in a "critical condition" on Saturday morning, but would not provide further details.

Field Day attracted more than 28,000 people to The Domain. Credit:Nicole Elphick

The one-day festival at The Domain in Sydney attracted more than 28,000 people who were eager to continue partying long after the New Year's Eve fireworks.

NSW Police said they arrested 184 revellers in relation to drug offences, including eight charged with drug supply.