Demi Moore is out of hospital after being treated for a reported seizure at a birthday party she threw at her home earlier this week.

Despite unconfirmed suggestions the hospitalization was due to inhaling the substance nitrous oxide, Moore's handlers say the seizure was due to stress and exhaustion.

Publicist Carrie Gordon said: "Because of the stresses in her life right now, Demi has chosen to seek professional assistance to treat her exhaustion and improve her overall health.

"She looks forward to getting well and is grateful for the support of her family and friends."

But new reports suggest that Moore has been abusing the drug Adderrall, which is a legal, amphetamine salts-based substance. Other sources have reported that Moore is anorexic and has been loading up on Adderrall and energy drinks instead of eating.

Meanwhile, unconfirmed allegations that Moore was dabbling with "whip-its" when she was taken to hospital this week has many wondering what exactly "whip-its" are, and why a wealthy Hollywood actress would be dabbling with them.

According to a report on gossip website TMZ, Moore was doing "whip-its" Monday night when she was rushed to hospital. TMZ says a friend of Moore's told paramedics that the actress had gone semi-conscious after inhaling the gas and falling into what appeared to be a seizure.

But many questions remain.

So what exactly is a "whip-it"? It's the street name for an inhalant that provides an easy though brief high. The inhalant is made of nitrous oxide, commonly known as "laughing gas."

Whip-its are named after the small metal canisters of nitrous oxide that can be used for recharging whipping cream cans. Recreational users sometimes fill balloons with the gas and then inhale the gas repeatedly to get a brief high.

Nitrous oxide is not considered toxic when delivered with oxygen, as it typically is when used as a dental anesthetic. But it can lead to hypoxia (decreased oxygen in the blood) if too much is inhaled at once, which might bring on seizures.

Long-term use of nitrous oxide can also cause serious health problems, such as severe vitamin B12 and folic acid deficiencies. This in turn can lead nerve damage.

As all celebrity watchers have learned, there's usually something suspicious when a publicist says a celebrity is suffering from "exhaustion." After all, exhaustion doesn't usually merit a 911 call, as Salon's Mary-Elizabeth Williams pointed out this week.

Moore has had issues with substance abuse in the past, reports. Still, celebrity watchers found the reports that Moore was doing whip-its surprising.

Gossip columnist Perez Hilton called the allegation "weird," noting that whip-its are "normally performed by teenagers who can't get their hands on an actual drug."