PHOTOS: Supermodels, stars go without makeup for Unicef

Could 'no makeup selfies' be the next ice bucket challenge?

In the wake of the viral sensation that raised more than $100 million for ALS charities, Unicef UK Ambassador Jemima Khan has started a similar trend to raise money for children affected by conflict in Syria.

Khan tweeted a morning selfie on Oct. 5 with the hashtag #wakeupcall, explaining how the movement works:

The trend has since spread to celebrities throughout the United Kingdom and then in the US. It's especially popular among models, like American Cindy Crawford, and some men have even joined.

Click through the gallery above to see which celebrities have joined the trend.

The nature of the new trend has faced some backlash. Critics say that the trend is about self-promotion by the stars, rather than the issue at hand. Unlike some varieties of the Ice Bucket Challenge, though, the origin of the Unicef campaign urges anyone who is nominated to donate.

According to Unicef USA, 6.5 million children have been affected by the conflict in Syria, including more than 1 million who are living as refugees in neighboring countries.

Whether or not you join the "no makeup selfie" trend, you can learn more about children affected by the conflict, including how to donate specifically to the cause, on Unicef USA's website.