Extended exposure to sunlight in summer increases serotonin production and vitamin D synthesis, which are linked to improved mood, greater energy and lower risk of seasonal depression.
How sunlight affects serotonin and wellbeing
Daylight stimulates neural pathways that increase the brain’s release of serotonin, a neurotransmitter associated with feelings of wellbeing, alertness and energy, which helps explain why many people feel more upbeat during sunny months.
Vitamin D production and mental health
Ultraviolet B radiation from sunlight enables the skin to produce vitamin D, a nutrient that supports bone health and has been linked to mood regulation and reduced symptoms of depression in observational studies and clinical reviews.
Circadian rhythms, sleep and daytime energy
Longer daylight in summer helps entrain circadian rhythms by providing stronger daytime light cues, improving sleep‑wake timing, daytime alertness and cognitive performance, which together raise daytime energy and wellbeing.
Risks of too much sun and how to balance them
While moderate sun exposure has mental‑health benefits, excessive ultraviolet exposure increases the risk of skin damage, premature ageing and skin cancer, so sensible limits, sunscreen and protective clothing are important to preserve long‑term health.
Practical tips
Aim for short regular periods of sunlight rather than long unprotected sessions, spend time outdoors in daylight to support mood and circadian timing, obtain vitamin D from a mix of safe sun exposure and diet or supplements when needed, and always practise sun safety to reduce harm.
Takeaway
Summer’s extra daylight can boost serotonin, help the body make vitamin D and strengthen circadian rhythms, which together raise mood and energy, but benefits should be balanced against the well‑documented risks of excessive sun exposure.