Although Pavel may be entirely right for your situation several other possibilities exist. A. His answer from one extreme, the child has been abused at night & desires to feel safer at night. (unlikely given some of the other context clues) If it's the case, she'll need to know it's safe to tell you even if the abuser threatened her if she tattled. But ask her if anything bad has happened anyway to rule it out. If it's the case, she'll need to know it's safe to tell you even if the abuser threatened her if she tattled. In the United States, child abuse is actually quite common & typically committed by someone known to & trusted by the family.

B. Your daughter simply wants to be close to you. Perhaps discussions in the evening & towards bedtime that she will be safe at night and you look forward to seeing her again in the morning?

C. Be aware that in some countries or cultures children sleeping in the same bedroom as the parents is quite normal. Of course the fact you prefer not to is something she needs to learn to respect.

D. Many other possible reasons for her behavior. Try to find out why she's doing this, and you'll have a better idea how to proceed...?

Some context: I must admit I'm more familiar with older children.

Also, look for related answers Why won't my toddler sleep when her mother tries to put her in bed? and can you give us some more information, any recent changes, pattern to this, etc.

Although Pavel may be entirely right for your situation several other possibilities exist. A. His answer from one extreme, the child has been abused at night & desires to feel safer at night. (unlikely given some of the other context clues) If it's the case, she'll need to know it's safe to tell you even if the abuser threatened her if she tattled. But ask her if anything bad has happened anyway to rule it out. If it's the case, she'll need to know it's safe to tell you even if the abuser threatened her if she tattled. In the United States, child abuse is actually quite common & typically committed by someone known to & trusted by the family.

B. Your daughter simply wants to be close to you. Perhaps discussions in the evening & towards bedtime that she will be safe at night and you look forward to seeing her again in the morning?

C. Be aware that in some countries or cultures children sleeping in the same bedroom as the parents is quite normal. Of course the fact you prefer not to is something she needs to learn to respect.

D. Many other possible reasons for her behavior. Try to find out why she's doing this, and you'll have a better idea how to proceed...?

Some context: I must admit I'm more familiar with older children.

Also, look for related answers Why won't my toddler sleep when her mother tries to put her in bed? and can you give us some more information, any recent changes, pattern to this, etc.