As the days become longer and evenings stay brighter, many people notice changes in their sleep. For some autistic people, people with ADHD, or people with highly sensitive traits, these changes can be especially noticeable.
Sleeping worse in spring or summer is not always simply a matter of “poor sleep hygiene”. For many neurodivergent people, sleep can be affected by a combination of factors: changes in light exposure, temperature, routine, sensory load and circadian rhythm.
Light and the body clock
Light is one of the most important signals the body uses to regulate its internal clock, also known as the circadian rhythm.
This rhythm helps organise many bodily functions, including the sleep-wake cycle, body temperature, melatonin release, alertness, and the times of day when we feel more sleepy or more awake.
When we are exposed to more light in the evening, melatonin release can be delayed. This may make it harder to fall asleep, even when someone feels exhausted.
In spring and summer, later sunsets can mean the body receives “daytime” signals for longer. For some people, this can shift their natural sleepiness later into the evening.
Daylight saving time and seasonal changes
It is important to distinguish between the clock change itself and the broader seasonal transition.
Daylight saving time can temporarily disrupt the sleep-wake rhythm for a few days. However, spring and summer also bring longer-lasting changes: later sunsets, warmer nights, more noise, allergies, social plans, travel, school holidays and less predictable routines.
All of these factors can affect sleep.
For many neurodivergent people, regularity and predictability are important for feeling regulated. When routines, schedules and the sensory environment change, the nervous system may need to work harder to adapt.
Why can this affect neurodivergent people more?
Autistic people and people with ADHD often experience differences in sleep, sensory processing, emotional regulation, executive functioning and circadian rhythm timing.
This does not mean that every neurodivergent person will sleep worse in spring or summer. However, it may mean that some people are more sensitive to certain environmental changes.
For example, one person may find it harder to switch off at night because there is still a lot of light. Another may feel more irritable because of heat, noise or increased social plans. Someone else may find it harder to wake up on time if their bedtime gradually shifts later.
In ADHD, there may also be a tendency towards a delayed circadian rhythm, meaning that sleepiness comes later and mornings can feel particularly difficult. In autistic people, sleep difficulties can be linked to multiple factors, including sensory differences, anxiety, changes in routine and possible differences in circadian regulation.
What can this look like?
Seasonal changes in light and routine may show up as:
- Difficulty falling asleep
- Difficulty waking up on time
- Waking earlier than usual
- More fragmented sleep
- Feeling “tired but wired”
- Increased irritability
- More emotional dysregulation
- Worsening concentration
- Greater sensory overwhelm in the evening
- Needing longer to recover after busy days
These changes can affect daily functioning. Poorer sleep can worsen attention, frustration tolerance, emotional regulation, sensory sensitivity and the ability to organise tasks.
It is not simply “poor sleep hygiene”
When someone struggles with sleep, they are often given very general advice: turn screens off, go to bed earlier, exercise more or relax.
Although some strategies can help, this kind of advice may be insufficient if the neurodivergent context is not understood.
For some neurodivergent people, the problem is not a lack of willpower or a lack of healthy habits. The nervous system may be responding to real changes in light, temperature, noise, routine and sensory load.
Understanding this allows us to approach sleep with more precision and less judgement.
What may help?
Some helpful strategies may include:
- Reducing bright light and screen use in the evening
- Using blackout curtains or an eye mask
- Using earplugs or noise-cancelling headphones if environmental noise interferes with sleep
- Keeping the bedroom as cool as possible
- Getting more natural light in the morning to help regulate the body clock
- Keeping wake-up time as consistent as possible
- Reducing sensory demands before bed
- Creating a transition routine towards bedtime
- Allowing some flexibility during seasonal changes
Morning light can be particularly important because it helps anchor the circadian rhythm. In contrast, too much bright light in the evening may send the brain the signal that it is not yet time to sleep.
A more compassionate approach
If sleep worsens in spring or summer, it does not necessarily mean that the person is doing something wrong.
It may be a sign that the body and nervous system are trying to adapt to an environment that has changed: more light, more heat, more noise, more activity and less predictability.
In neurodivergent people, sleep is often multifactorial. Instead of reducing everything to “sleep hygiene”, it may be more useful to ask:
What has changed in the environment?
Which sensory inputs have increased?
Has the routine become less predictable?
Are there more social or sensory demands?
Is morning and evening light helping or interfering?
Understanding these factors can help create support that is more realistic, individualised and respectful.
Sleep does not happen in isolation. It happens within a body, a nervous system and an environment. For many neurodivergent people, seasonal changes can have a bigger impact than we realise.
Thanks for reading! we welcome any comments or questions.
References
Carmassi C, Palagini L, Caruso D, et al. Systematic review of sleep disturbances and circadian sleep desynchronization in autism spectrum disorder: toward an integrative model of a self-reinforcing loop. Frontiers in Psychiatry. 2019;10:366.
Coogan AN, Baird AL, Popa-Wagner A, Thome J. Circadian rhythms and attention deficit hyperactivity disorder: the what, the when and the why. Progress in Neuro-Psychopharmacology & Biological Psychiatry. 2016;67:74–81.
Gooley JJ, Chamberlain K, Smith KA, et al. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463–E472.
Wright KP Jr, McHill AW, Birks BR, Griffin BR, Rusterholz T, Chinoy ED. Entrainment of the human circadian clock to the natural light-dark cycle. Current Biology. 2013;23(16):1554–1558.
Romigi A, Franco V, et al. The effects of daylight saving time and clock time transitions on sleep and sleepiness: a systematic review. Sleep Medicine Reviews. 2025.