As the UK emerges from the darker winter months, the arrival of spring brings lighter evenings and milder weather. You might even notice you’re in a better mood! But this seasonal boost isn’t just your imagination.
Science shows that longer days and increased sunlight can affect your mental and physical wellbeing, for the better. In this blog, we look at the science behind your spring mood boost – and how to maximise it.
1. More Daylight = More Serotonin
Sunlight plays a key role in regulating serotonin, the “feel‑good” hormone. When daylight increases in spring, your brain naturally ramps up its serotonin production.
A study of over 400k adults found that each additional hour spent outdoors during daylight hours was linked to lower depression, less frequent low mood, and greater happiness. UK adults in the study got just 2.5 hours of daylight a day – showing you only need a small amount of time outside to make a difference.[i]

2. Spring Helps Reset Your Body Clock
Short winter days can disrupt your body’s circadian rhythm. Your circadian rhythm is like an automatic timer inside your body that tells you when to get up and go to sleep. If this is disrupted, it can lead to grogginess and insomnia. When spring increases daylight hours, your internal clock begins to realign. Here are just some of the things your circadian rhythm can control:
- 😴 Sleep and wake times
- 🧠 Mood and focus
- ⚡ Energy levels
- 🍽 Appetite and digestion
- 🌡 Body temperature
- 🧘 Hormones like melatonin (sleep hormone) and cortisol (alertness hormone)
According to research on UK adults, more daytime light exposure is associated with fewer insomnia symptoms, greater ease of waking, and feeling naturally awake earlier. In other words, longer days help your sleep and mood to get back on track. [ii]
3. Vitamin D Levels Improve (And That Really Matters in the UK)
Unsurprisingly, a lack of vitamin D is a widespread health issue in the winter.
Recent UK data shows that around 50% of UK adults don’t get enough vitamin D. With 56% of 18-29 year olds having especially low levels. [iii]
When sunlight hits your skin, your body makes vitamin D all by itself. Specifically, UVB rays trigger this process.
Vitamin D Facts:
- You can’t get vitamin D through a window.
- In northern countries (like the UK), the sun is too weak from about October to March to make vitamin D.
- Skin tone matters: darker skin needs more sun exposure to make the same amount of vitamin D.
Why is Vitamin D important?
Supports mood and mental health
Vitamin D plays a role in, regulating mood, brain function, possibly reducing risk of depression and low mood
Supports the immune system
Vitamin D helps your immune system fight infections, reduce excessive inflammation and function in a balanced way
Helps regulate sleep
Vitamin D interacts with Melatonin (your sleep hormone) and your Circadian rhythm (your body clock)
Muscle strength and energy
Adequate vitamin D helps with muscle function, and reducing muscle aches and weakness.
4. Spring Helps Relieve Seasonal Affective Disorder (SAD)
SAD affects millions in the UK, and lighter days play a significant role in easing symptoms.
The NHS says around 2 million people experience Seasonal Affective Disorder each year as the winter darkness sets in [iv]. Other surveys suggest about 3 in every 100 people facing more serious winter depression and as many as 1 in 15 are dealing with milder seasonal low mood[v].
As spring brings increased natural light, serotonin levels stabilise and melatonin production normalises – mood commonly improves. For more information read our blog: What is Seasonal Affective Disorder, and how can you combat it?
5. Getting Outdoors Reduces Stress
Spring’s arrival makes it so much easier to enjoy time outdoors. Trees becoming green again, flowers starting to bloom and the weather finally warming up.
Being out in nature naturally helps you unwind. According to a Loughborough University study Even just 15 minutes a day in nature is enough to boost your mood, concentration and physical health. Spending time in nature can lift your mood by helping you:
- feel happier and more positive
- easing feelings of sadness and anxiety
- and quietening repetitive negative thoughts.
Getting outdoors is also shown to reduce blood pressure and your resting heart rate[vi].

6. Longer Days Boost Activity and Social Connection
Longer days means it suddenly feels so much easier to get outside and get moving. The extra daylight gives you the chance to book in after‑work walks, garden workouts, or meeting friends outdoors.
Lighter evenings also make socialising feel effortless again – the kind of simple connection that can lift your mood without you even noticing.
And if you’re looking for fun ways to make the most of that extra daylight, Vavista has a great roundup of outdoor workouts to help you feel energised and inspired.
7. Spring Feels Like a Fresh Start
Longer, sunnier days don’t just change our biology, they influence our psychology. Many people feel more hopeful and optimistic as spring arrives.
This uplift is rooted in physiology: more light = more serotonin and less melatonin. But it’s also cultural and behavioural. UK surveys show that people overwhelmingly associate sunlight with better sleep, improved mood, and stronger overall wellbeing.[vii]

So this spring, make the most of the lighter days: get outside, seek out natural light early on, and build simple outdoor habits that support your mental wellbeing. And if you enjoyed reading this, you might also like Vavista’s guide to managing stress in everyday life.
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