SAN JOSE MINE, Chile (AP) — A team of NASA doctors and engineers recommended Friday that Chilean authorities regulate the day-and-night sleep patterns of 33 trapped miners, boost their Vitamin D intake and phase in an exercise program as their nutrition improves.

The NASA team is in Chile to help rescuers develop plans for maintaining the health of miners, who have been buried nearly a half-mile underground since a mine collapse on Aug. 5. The miners organized themselves and rationed food for more than two weeks until they were discovered alive on Aug. 22.

Since then, the miners have been receiving food, water and medicine through three bore-holes.

The NASA team, which spoke at a news conference late Friday, said regulating sleep patterns requires establishing a "lighted community area" that is always lit and a "dark sleeping area" that is always shuttered. Regulating the time the miners eat and exercise would help them get in a pattern, NASA experts said.

Geologists and engineers are working to open a rescue shaft to the workers, but the government has said it could take up to four months to drill the hole. Possible alternative plans, set to get under way over the next week, could be faster.

The team leader, Dr. Michael Duncan, said he is impressed by how Chilean rescuers are maintaining the men in the meantime and preparing them for what will be a harrowing rescue.

"They are basically writing the book on how to rescue this many people this deep and underground for so long," Duncan said.

Underscoring the unprecedented nature of the rescue, Duncan said the protective cages that will be used to bring the men up must be specially made, and his team will participate in the design.

The miners are also getting support from a group of former rugby players who survived more than two months of isolation in the Andes four decades ago.

Ramon Sabella, Pedro Alcorta, Jose Inciarte and Gustavo Servino were among 16 Uruguayans who survived a plane crash in the snow-covered peaks and waited 72 days to be rescued. Some were forced to eat the flesh of friends killed in the crash to stay alive.

The four ex-players arrived Friday in the Chilean capital, Santiago, and met with President Sebastian Pinera.

Sabella said the group would visit the San Jose mine in the northern town of Copiapo on Saturday to deliver a message of hope and support from Uruguayan children.