This is more during her bed time. Thank you.
Most children have fears of various kinds, and are especially likely to have fears at bed time. It is not entirely clear what kinds of bad incidents your daughter might have in mind--and whether these are fairly universal fears of monsters and robbers or whether your daughter may have had some personal exposures to danger or loss which trouble her particularly. Any difficulty in a child's life such as family conflict, economic hardship, or health problems may be translated by a worried child into fears of the dark. The answer here may involve not just reassuring the child about the dark, but helping the child to understand and to cope with the particular stresses being faced during the day. So your question can have a fairly broad answer, depending on the situation.
Sometimes it is helpful to tell an anxious child that the parent will sit by the child's bed until the child falls asleep. This takes place after the usual nighttime ritual of conversation or reading or whatever sociable interactions the parent has with the child before the child turns off the lights. The parent then sits quietly in the dark, without chatting or getting drinks of water or engaging in any activity, until the child falls asleep.
Talking about whatever is bothering your daughter--whether it involves her schoolwork, her friends, or family matters--will also help her feel supported of course. Spending a bit of extra time having fun together may give her the oppprtunity to share with you what is on her mind. If her worries seem to persist, you can ask your pediatrician for help or for a referral to a mental health professional.
Elizabeth Berger MD
Child Psychiatrist and author of "Raising Kids with Character"