While the many reported reasons for [article id="1677859"]Demi Moore's recent hospitalization[/article] have varied from exhaustion to substance abuse, TMZ is now saying nitrous oxide was behind the health scare.

According to the website, friends who were on the scene the night of the hospitalization told EMTs the actress was inhaling nitrous oxide from aerosol cans -- also known as whip-its -- before 911 was called. TMZ's sources said the actress was exhibiting seizure-like symptoms after inhaling the nitrous.

[article id="1677885"]Demi's hospitalization caps a rough patch for the actress.[/article]

People magazine also talked to sources close to Moore, who said they've been worried about their friend for quite some time. "Really, it was over the last year her friends saw a change," one source said about her split from husband Ashton Kutcher. "She wasn't sleeping as well, didn't seem to be eating and looked really gaunt."

Another source told the mag that Moore's recent prescription-drug abuse was a factor in the end of her marriage. "It was a sticking point for Ashton," the source said. "He wanted her to take care of herself and get a hold of things, and she wouldn't."

Check out photos of Demi and Ashton from happier times.

Moore endured a very public and emotional split from Kutcher back in November, publicly announcing the breakup with "sadness and a heavy heart" after months of not-so-quiet rumblings that her husband had been unfaithful. While it was announced earlier this month that Moore would star as feminist icon Gloria Steinem in the upcoming film "Lovelace," her rep said the setback in her health would prevent her from working on the project.