Why Is My Neurodivergent Child Struggling More in Autumn?
It is the third meltdown this week, and it is only Wednesday. The routine has not changed and neither has school, yet your child is coming home wound tight, falling apart over a sock seam, and lying awake long after lights out. You may have started to wonder whether it is something you are doing.
Behaviour like this is rarely random. It reflects what is happening in your child's biology, and autumn asks a great deal of a nervous system that is already working hard to stay regulated. Whether autumn arrives for you in September or in March, several things tend to shift at once: the light, the routine, the clothes and the food on the plate. Once you can see those shifts, a hard season starts to make a lot more sense.
What changes in autumn, and why your child feels it
Less daylight. Sleep problems are reported in an estimated 50 to 80 percent of autistic children, and research consistently links ADHD with a later body clock, including a later evening release of melatonin, the hormone that tells the body it is time to sleep. Darker mornings and evenings put extra pressure on a sleep system that may already be running behind.
New routines. Autumn often brings a new term, new teachers or new activities. For autistic children, a strong need for sameness is part of the diagnostic picture itself, so changes that look small to an adult can feel very large to a child.
More sensory input. Heavier clothing, tights, coats, wet shoes and more time indoors all change what the senses are dealing with each day. Differences in sensory processing are also part of the diagnosis of autism, which is why a scratchy jumper can be enough to unravel a morning.
Less vitamin D. Most of our vitamin D is made in the skin in response to sunlight. The further you live from the equator, the longer the stretch of the year when the sun is too weak for the skin to make much of it at all.
Food that may already be a struggle. Autistic children are around five times more likely than their peers to have feeding difficulties such as strong food selectivity, and research has found lower average intakes of protein and calcium.
Why it shows up as behaviour
When sleep is short, the senses are busy and the routine has shifted, a child has far less capacity left for everything else. In autistic children, disrupted sleep has been linked with more challenging behaviour and more pronounced autism symptoms. What looks like defiance may be a signal from a nervous system with nothing left in reserve.
Where nutrition can help this autumn
Food will not change the length of the days, but it can support the systems under the most strain. These are sensible places to start.
1. Find out about vitamin D rather than guessing
Meta-analyses have found that, on average, autistic children and children with ADHD have lower vitamin D levels than their peers. That is an association, and it does not prove that low vitamin D causes symptoms. Trials of supplementation have also produced mixed results. What it does suggest is that autumn is a good time to find out where your child's levels actually sit. A blood test gives you a baseline, so that any supplement is based on your child's result rather than a guess.
2. Protect protein, especially at breakfast
Because research has found lower average protein intake in autistic children, breakfast is a practical place to add some. Simple options include:
eggs, cooked the way your child already accepts them
natural yoghurt with fruit
nut or seed butter on toast
cheese, or leftovers from last night's dinner
3. Support the gut with fibre and fluids
Gut symptoms are markedly more common in autistic children, and a 2023 meta-analysis found constipation in around 37 percent of them. Researchers have urged clinicians to check for gut problems when an autistic child's behaviour changes without a clear reason, because discomfort a child cannot easily describe may come out as distress instead.
Autumn produce makes fibre easier to include. Apples, pears, root vegetables, squash, lentils and beans can all be roasted, baked or blended into soups. Keep fluids up alongside the fibre, and remember that warm drinks and soups count too.
4. Work with a selective eater, not against them
If your child eats a limited range of foods, a hard season is not the moment to overhaul their plate. Keep changes small and low pressure:
offer a new food alongside a safe one, with no expectation to eat it
keep textures familiar
change one thing at a time, such as a new vegetable roasted the same way as one they already eat
Use the light you have
Light is the body clock's strongest signal. In studies, morning bright light has shifted the body clock earlier in both children and adults with ADHD. Getting outside in daylight in the morning, even on the walk to school, is a simple way to give the body clock that signal while there is still light to use.
Your child is not an average
The research describes averages across groups of children. Two children with the same diagnosis can have very different things going on with their sleep, their gut and their nutrient levels. That is why a functional medicine approach starts by understanding your child's biology, sometimes with testing, before making recommendations.
If autumn is already feeling hard in your house, and the sensible changes are not shifting it, you are welcome to book a discovery call to talk through what you are seeing.
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