what is recommended amount/percent of natural light in a childcare setting while children sleep? Thanks

The amount & type of light in a baby’s sleep environment is important for adequate supervision. Whatever light source is used; it needs to be sufficient to provide visual supervision of baby sleeping
& regular checking of breathing & colour of skin.

ACECQA has the following -

Educators should closely monitor sleeping and resting children and the sleep and rest environments. This involves checking/inspecting sleeping children at regular intervals, and ensuring they are always within sight and hearing distance of sleeping and resting children so that they can assess a child’s breathing and the colour of their skin

Service providers should consider the risk for each individual child, and tailor Sleep and Rest Policies and Procedures (including the frequency of checks/inspections of children) to reflect the levels of risk identified for children at the service. Factors to be considered include the age of the child, medical conditions, individual needs and history of health and/or sleep issues.

https://www.acecqa.gov.au/resources/supporting-materials/infosheet/safe-sleep-and-rest-practices