Sleeping Curse

The sleeping curse is a powerful curse that, when consumed, places its victims into a state of deep sleep, relocating their souls to a Netherworld.

History
The sleeping curse is first used by Maleficent on Aurora's mother, however, it is said that this sleeping beauty "got the better of her". After it fails, Maelficent trades it away to the Evil Queen in exchange for her Dark Curse. ("The Thing You Love Most"/"Broken")

Queen Regina combines the curse with an apple which she blackamiles Snow White into eating with the threat of killing her Prince Charming. Charming is freed from Regina by the Huntsman and sets out to find Snow, when he does, he is too late as she is already lying in her glass coffin, however, he asks the dwarfs to lift it so he can say goodbye. He kisses his sleeping princess and she awakens after a burst of true love is released. ("Pilot"/"An Apple Red as Blood"/"A Land Without Magic")

Regina desperately wants to get rid of Emma Swan and so uses Jefferson and his hat to retrieve her poisoned apple from the fairytale land that was, she then bakes this apple into a turnover which she gives to Emma, planning on it affecting her. However, desperate to find proof of the Dark Curse, Henry eats the turnover, sending him to sleep. Henry is taken to hospital where, soon enough, he is awoken by true love's kiss from Emma, who not only breaks Henry's curse with it, but the Dark Curse as well.

Maleficent uses the curse a second time on sleeping beatuy's daughter, Aurora. sending her into a deep sleep which lasts 28 years until the breaking of the Dark Curse. Her true love, Prince Phillip, and his travelling companion, Mulan, rode to her rescue and the former awakes her with true love's kiss. Side effects of Aurora's awakening includes terrible dreams of a burning, red room which exists in the Netherworld, she later uses this to talk to Henry who is having the same nightmares as a result of the sleeping curse that effected him. ("Tallahassee"/"Child of the Moon"/"Into the Deep")

David is desperate to communicate with his beloved Mary Margaret via the Netherworld and so he requests the Regina make him a sleeping curse. She does so and dips a needle in the potion, Mr. Gold places it on a spinning wheel, and, when David pricks his finger, he is sent to sleep. He meets Mary Margraet in the Netherworld who got there by sending herself into a deep sleep via powder made from poppies, he gives her all the information she needs before she wakes up and he remains trapped. David remains asleep until Mary Margaret and Emma's eventual retrun in which the former rushes to David's aid, giving him true love's kiss which wakes him up, much like he did for her.