Your toddler never used to mind hitting the sack with the lights off. But all of a sudden, she wants you to keep the lights on in her bedroom — or she wakes in the middle of the night and is afraid of falling back asleep on her own.

Things that go bump in the night are a normal part of everyday life to adults, but to toddlers they can be downright terrifying.

Why is my toddler suddenly afraid of the dark?

Once a toddler’s thought process becomes more sophisticated, fears can appear to make kids anxious about a whole array of stuff — especially at night, when it’s easy for anyone’s imagination to run wild.

In addition to a rich fantasy life, toddlers are more aware of the larger world and its dangers. They have longer memories than babies do, so a negative experience (like falling off a swing) may trigger a longer-lasting fear.

Toddlers are also highly suggestible: Your little one might assume, for example, that the monster hiding in the girl’s bedroom in the book you read last night could show up in her room as well. Or, if a sibling is afraid of the dark, your little one might decide that’s enough reason for her to be afraid too.

Changes (a move to a new home, the arrival of a new sibling) can also cause a child to feel insecure and afraid.

When does a fear of the dark typically start and end?

Children are most often afraid of the dark starting at around the age of about 2 through the preschool years, although it can appear in older children as well. A fear of the dark usually lasts for a few weeks to a few months.

What can you do about your toddler's fear of the dark?

A few strategies can help keep your toddler’s imagination in check and help her to self-soothe and feel secure alone at night:

Acknowledge the fear

While a fear of the dark may seem irrational to you, it’s very real to your toddler — so ignoring it won’t make it go away. In fact, ignoring or playfully teasing a fear can magnify it.

Instead, let your child talk about her dread ("Tell me what's scaring you") without denying her feelings (don't say: "Big girls aren't afraid of the dark"). Be reassuring ("I'll be close by if you need me") without making too much of the fear or overdoing the attention.

Stay in bed and keep the lights off

When you heed your child's calls in the middle of the night, don't reach for the light or bring her to your bed. To help her learn to overcome her fears, have her stay in her own bed and comfort her in the dark.

If your little one just can’t fall back asleep without you, it’s better for you to sleep in her room than for her to sleep in yours. Just try to avoid sleeping in the same room too often, since that might encourage your little one to become dependent on you to sleep.

Play in the dark

Try to make fun associations with the dark by having a treasure hunt for glow-in-the-dark objects or hunting for fireflies in the backyard.

Try relaxation training

Before bedtime, close your eyes in the dark together and imagine a relaxing scene, like playing at the beach.

Offer a security object

As long as your child is over 1 year old (so as not to risk sudden infant death syndrome, or SIDS), give her a security object like a favorite stuffed animal, for example, to help her feel more secure and relaxed throughout the night.

Leave a little light on

A night light can go a long way toward melting a child's fears. Choose one no brighter than 4 and 7 watts, and look for a yellow- or amber-colored light bulb, avoiding white- or blue-colored light.

Or consider leaving her door slightly ajar and the hall light on. She may be comforted by the sliver of light and household noises.

Check on her

Tell your little one you’re right next door, then pop your head in every five to 10 minutes until she falls asleep if she’s anxious about you leaving her room.

Work with her imagination

If she's convinced there's a troll in her closet, do a search. You can also appoint a favorite toy to stand guard, or teach your child a special word to ward off trolls.

You can also arm her with a lucky charm like a flashlight, magic wand or spray bottle filled with anti-troll potion.

Applaud bravery

Make a big deal when your child confronts her fear — no matter how small the step.

You might even want to create a star system to award your child for being brave on her own if she stays in her bed with the lights off all night long. A mini celebration or a tiny treat may well be in order.

How can you prevent a fear of the dark?

To help prevent a fear of the dark, steer clear of scary TV shows, movies and books. And avoid threats that can have a toddler’s imagination running wild ("If you don't behave, the troll will get you").

Heads up: Teasing or employing logic ("See, your room looks the same with the lights turned on or off") can have the opposite effect. These tactics may make her more fearful because she'll think you don't understand the danger she believes is very real.

Plus, teasing can zap a child's self-esteem. Instead, reassure your toddler that she's safe, even in the dark.