Will dim lights in the evening increase melatonin and make sleep easier for your toddler?
Should you dim the lights in the evening to bring on your little one’s sleep?
Melatonin is secreted by your brain, and your child's brain at night. Melatonin tracks or follows sleep cycles, but it doesn't drive sleep cycles. You can find out about the science of melatonin here and here.
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By far the most powerful biological force which controls your toddler's sleep in the evenings is sleep pressure.
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The other biological force which effects your toddler's bedtime is your child's body clock.
You might have heard that you should dim the lights in the evening to increase your toddler’s melatonin levels, which will help her go to sleep. This might be accompanied by advice that it is also important not to overstimulate your little one in the evenings. You might even hear that these two strategies will keep her cortisol levels low.
Unfortunately, none of this advice is unhelpful or true, and can even make sleep even worse for your family. The melatonin produced by your own body or your toddler's body doesn't bring on sleep.
Dimming the lights in the evening
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Reduces visual and sensory experience, so that your toddler is more likely to dial up, which makes it harder for the sleep pressure to do its job.
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Might quickly result in a conditioned dialling up. Your baby learns that the dimming of lights is the beginning of a miserable time of day, and so she starts to dial up as soon as you dim them!
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Might even result in a conditioned dialling up of your own sympathetic nervous system. Having to dim the lights and start bedtime routines in the evening can be depressing for parents. We might begin to dread this time of day, with its enforced family quietness and muted lighting or lengthy efforts to get our little one to sleep.
Instead, it’s best to work out how you can most enjoy yourselves as a family in the evening, providing rich sensory motor nourishment for your toddler, without worrying about having to stay home or having to dim the lights!
If you don't need to dim the lights, then how can you make bedtime and sleep easy?
At bedtime, many families switch on a bedside light and switch off the main lights as as they snuggle down with their little one for a feed or a story or a cuddle. You might do this when you've made the judgement that your little one’s sleep pressure is high enough. Or your toddler might fall asleep in the evenings once the sleep pressure is high out in the living area or when you’re at a friend's home socialising! You don’t have to worry about special cots, the lights, or quietness.
You can rely upon sleep pressure to send your toddler to sleep each evening, as long as
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She is dialled down
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Her body clock settings are in sync with yours.
Keeping your toddler's body clock and sleep pressure in sync with your own requires large doses of rich sensory motor nourishment in the evenings – often a hard thing to provide at the end of a day, when you’re already exhausted. Planning ahead about how to best enjoy the evenings together really helps families, and even more so if you're doing evenings without the support of another adult.
Unfortunately, dimming the lights usually doesn’t.
Recommended resources
Melatonin supplementation doesn't help with toddler sleep
Melatonin research doesn't support the belief that dimming the lights helps with infant sleep
Can giving baby your expressed breast milk be 'mistimed' because of melatonin levels?
Melatonin: production in babies (term + preterm) and supplementation
Selected references
Owens J, Barnett N, Lucchini M, Berger SE. Melatonin use in infants and toddlers. Sleep Medicine. 2024;120:53-55.
There are many references available under the Recommended resources articles.
