As winter comes to an end and the days become longer, many people describe feeling unusually tired, irritable, mentally foggy or simply “not quite themselves”.
This is sometimes referred to as spring fatigue or spring asthenia.
Although the experience is commonly reported, spring asthenia is not an official medical diagnosis, and the scientific evidence does not currently support it as a distinct seasonal syndrome.
In fact, a recent longitudinal study published in 2026 found that although almost half of participants reported experiencing spring fatigue, researchers did not find a consistent seasonal increase in fatigue, daytime sleepiness, insomnia or poorer sleep quality.
So why do some people genuinely feel different when spring arrives?
Rather than there being one single cause, the transition into spring brings several changes at the same time — light exposure, sleep schedules, temperature, allergens, routines, social demands and sensory input.
For some people, particularly those who are neurodivergent, adapting to all of these changes may require additional energy.
Longer days and our biological clock
Light is one of the most powerful signals regulating our circadian rhythm — the internal biological clock that helps determine when we feel awake and when we feel sleepy.
As spring arrives, daylight increases rapidly and evenings become progressively brighter.
In countries that observe daylight saving time, there is also an abrupt one-hour shift in the social clock.
Although one hour may seem insignificant, our biological clock does not necessarily adjust immediately.
Research suggests that the spring transition to daylight saving time can temporarily reduce sleep duration, disrupt sleep quality and increase daytime sleepiness. Some people appear to be more affected than others, particularly those with a later chronotype.
For someone who already experiences difficulties with sleep or circadian regulation, even relatively small changes may therefore be noticeable.
What about melatonin and serotonin?
You may sometimes hear spring fatigue explained as being caused by sudden changes in “melatonin and serotonin levels”.
The reality is more complex.
Light exposure directly influences the circadian system and the timing of melatonin secretion. Morning and evening light therefore play an important role in regulating sleep-wake timing.
Serotonin is also involved in mood, sleep and circadian biology, but spring fatigue cannot simply be explained as a temporary serotonin imbalance.
It is more accurate to think about the transition into spring as a change in the environmental signals our brain uses to regulate sleep, alertness and behaviour.
Spring allergies can contribute to fatigue
Spring also means increased exposure to pollen for many people.
Allergic rhinitis does not only cause sneezing, itchy eyes and nasal congestion. It is also associated with poorer sleep, daytime sleepiness and fatigue.
Congestion can interfere with sleep quality, while the inflammatory response associated with allergies may contribute to feeling generally unwell or exhausted.
There is another factor to consider: some antihistamines can themselves cause drowsiness.
Older, first-generation antihistamines are particularly sedating. Newer antihistamines are generally less sedating, although individual responses vary.
If you notice increased fatigue or brain fog during allergy season, it is therefore worth considering both the allergy itself and the medication being used to treat it.
Why might seasonal changes be particularly noticeable for neurodivergent people?
Autistic people and people with ADHD may already experience differences in sleep, sensory processing, executive functioning and emotional regulation.
This does not mean that every neurodivergent person will struggle during spring.
However, several environmental changes can happen simultaneously, and this may increase the overall demand placed on the nervous system.
Sensory overload
Spring can dramatically change the sensory environment.
There may suddenly be:
- brighter and longer-lasting daylight
- more outdoor noise
- birds early in the morning
- lawn mowers and construction noise
- stronger smells from flowers and freshly cut grass
- warmer temperatures
- different clothing and textures
For someone with sensory sensitivities, these apparently small changes can accumulate.
The result may be increased overwhelm, irritability, exhaustion or a greater need for recovery time.
Changes in routine
Spring can also disrupt established routines.
Daylight saving time, Easter holidays, school holidays, changes in family schedules and longer evenings may all alter the predictability of daily life.
For some autistic people, predictability and routine are important forms of regulation.
For people with ADHD, changes in external structure can also make organisation, sleep routines and time management more difficult.
Even positive changes can require adaptation.
Increased social demands
Warmer weather often brings more invitations, outdoor activities, family plans and social expectations.
For some neurodivergent people, this can mean a sudden increase in the amount of social and sensory processing required.
Something can be enjoyable and exhausting at the same time.
A busy weekend of socialising may therefore require more recovery time than other people expect.
Emotional regulation
Sleep deprivation, sensory overload, allergies, changing routines and increased social demands can all affect emotional regulation.
If someone already finds emotional regulation more effortful, the cumulative effect may present as:
- increased irritability
- feeling more easily overwhelmed
- reduced frustration tolerance
- anxiety
- difficulty concentrating
- greater emotional reactivity
- shutdowns or meltdowns
- needing more time alone
Rather than assuming that these changes represent deterioration in mental health, it can be useful to consider what has changed in the person's environment.
Could it be Seasonal Affective Disorder?
Most people associate Seasonal Affective Disorder (SAD) with winter.
This is indeed the more common pattern: depressive symptoms typically begin during autumn or winter and improve during spring or summer.
However, a less common summer-pattern SAD also exists. In these cases, depressive symptoms emerge during spring or summer.
Summer-pattern SAD may include symptoms such as insomnia, reduced appetite, anxiety, agitation or restlessness.
Therefore, persistent or significant seasonal changes in mood should not automatically be dismissed as “spring fatigue”.
If symptoms are substantial, recurrent or interfering with daily functioning, a proper clinical assessment is appropriate.
What can help?
There is no specific treatment for “spring asthenia” because it is not a recognised medical disorder.
Instead, it is more useful to identify which aspects of the seasonal transition are affecting you.
Protect your sleep
Try to keep your wake-up and bedtime reasonably consistent, particularly around the clock change.
Blackout curtains, blinds or an eye mask can be useful as evenings become brighter.
Reducing bright light and stimulating screen use before bed may also help your brain transition towards sleep.
Morning daylight can help anchor the circadian rhythm.
Melatonin may be appropriate in certain circumstances, but timing matters considerably when it is being used for circadian purposes. Discuss its use with a healthcare professional rather than simply taking increasingly high doses.
Adapt your sensory environment
There is no reason to tolerate unnecessary sensory discomfort simply because the season has changed.
Depending on your sensory profile, this might include:
- sunglasses or tinted lenses
- noise-cancelling headphones or earplugs
- blackout curtains
- softer lighting at home
- comfortable, temperature-appropriate clothing
- keeping bedrooms cool
- planning quieter periods during busy days
The aim is not to avoid the outside world, but to reduce unnecessary sensory load.
Be selective with your commitments
Longer days can create the impression that we should be doing more.
You do not have to fill every additional hour of daylight with activities.
If social events are tiring, consider allowing recovery time before or afterwards rather than scheduling several demanding activities consecutively.
Manage allergies
If seasonal allergies are affecting sleep, energy or daily functioning, appropriate treatment can make a meaningful difference.
Remember that some antihistamines can cause sedation, so speak to your doctor or pharmacist if you notice significant daytime sleepiness.
Other practical measures, such as reducing indoor pollen exposure or using appropriate air filtration, may also help depending on your circumstances.
Look after the basics
Regular meals, adequate hydration, physical activity and sufficient sleep are not cures for neurodivergence or seasonal fatigue.
However, when the nervous system is already adapting to environmental change, neglecting basic physiological needs can make fatigue and emotional regulation more difficult.
Give yourself time to adjust
Perhaps the most useful message is that adaptation takes energy.
A change of season can alter light, temperature, sensory input, routines, sleep and social expectations almost simultaneously.
Some people barely notice these changes. Others notice them considerably.
For neurodivergent people, understanding your individual pattern can be more useful than trying to force yourself to adapt at the same speed as everyone else.
If you consistently notice changes at particular times of year, keeping track of sleep, mood, allergies, sensory overload and daily routines may help identify what is actually contributing.
And if fatigue, sleep disturbance or changes in mood are persistent, severe or significantly affecting your functioning, it is important not to assume that they are simply seasonal. Other physical or mental health causes may need to be considered.
The information provided is for educational purposes only and is not a substitute for an individual medical assessment.
Thanks again for reading! comments welcomed.
References
Blume, C., & Vorster, A. (2026). No evidence for seasonal variations in fatigue, sleepiness and insomnia symptoms: Spring fatigue is a cultural phenomenon rather than a seasonal syndrome. Journal of Sleep Research, 35(4), e70319. https://doi.org/10.1111/jsr.70319
Harrison, Y. (2013). The impact of daylight saving time on sleep and related behaviours. Sleep Medicine Reviews, 17(4), 285–292. https://doi.org/10.1016/j.smrv.2012.10.001
National Institute of Mental Health. (2025). Seasonal affective disorder. National Institutes of Health.
Pratt, E. L., & Craig, T. J. (2007). Assessing outcomes from the sleep disturbance associated with rhinitis. Current Opinion in Allergy and Clinical Immunology, 7(3), 249–256. https://doi.org/10.1097/ACI.0b013e3280f3c09f
Steponenaite, A., Wallraff, J. P., Wild, U., Brown, L., et al. (2026). A systematic review of epidemiological studies into daylight-saving time and health identifying beneficial and adverse effects. European Journal of Epidemiology, 41, 419–433.
Veneruso, M., Barbieri, A., Silvestrini, G., De Grandis, E., et al. (2026). Sleep in autism spectrum disorder: A systematic update. Current Sleep Medicine Reports, 12, Article 39.