Do you have more or less sex in the heat?

But although we know that the serotonin we get from the sunlight helps to make us feel happy, less stressed and more energetic, too much of it actually reduces libido. Instead of leaving us relaxed and in the mood for sex, a lot of serotonin is more likely to keep us focused on work.

On the other hand, surveys carried out by London dating sites suggest that the sun (and the skimpy clothing it encourages) tends to inspire more of us to get down and dirty. So which factor is dominating our summer sex drives? I went along to Green Park to ask Londoners basking in the sun whether they are having more or less sex in the heat of the summer.

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Sam, 23, student
"I'm lazy and I'd really rather be cool than have sex. I don't actively avoid it but I'm just not in the mood as much and I don't bother initiating it."

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Gokser, 38, doctor
"Definitely more. Why not, after all? It's natural to have more sex in the sun. It's instinct."

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Vanessa, 23, IT consultant
"It's sometimes a bit too hot to have sex. That bloated feeling you get in the heat puts me off and in the winter it's nice to snuggle."

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Vitali, 20, student
"Of course, more. Mostly because you can do it outside but also because the good weather and the heat puts you in a good mood."

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Lachland, 26, recruitment consultant
"You definitely have more sex in the winter — for body warmth. In the heat there's the sweat factor and you have to have a cold shower when you're done — or have sex in the shower."

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Mary, 50, social worker
"The heat makes you feel sexier and the sun gives you a sense of well-being. You wear fewer clothes and so does everyone else — so you can see more of the attractive men."

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Dave, 42, carpenter
"I always want to have more sex in the summer because the sun makes me really horny but it always means getting hot and sweaty, which turns me off."

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Keiran, 24, recruitment consultant
"I have sex whenever my girlfriend will let me but probably more at this time of year. Also, I'm bigger in the summer ..."

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Sarah, 50, social worker
"Of course on holiday you have more sex because you're more relaxed but generally I hate it when it's really hot. It doesn't do it for me. On a cold winter night it's really nice in bed."