We all know that being in love is a heavenly sensation, but what's it actually doing to your body? The answer is, it turns out, a great deal of good. We look at the physical effects of falling for someone, and why it can be so, so good for us.
Are you sleeping better? Losing weight more easily? Not coming down with flu even though all the others in your office are dropping like flies? Chances are, you're in love. Experts seem to agree that, as a result of side-effects ranging from plummeting blood pressure and steadying hormone levels to burning calories in the sack and fighting bad stress with good, falling for someone means you've struck health gold.
"The course of true love never did run smooth," wrote William Shakespeare. But what did he know? Here are our top reasons why you should be thankful you've hooked up this 14 February.
It increases your lifespan
While some may joke that tying the knot is "throwing your life away", it turns out they couldn't be more wrong. Research has shown over and over that married couples - even more so than those cohabitating - have longer lifespans. The main reason is that most people in healthy long-term relationships are less stressed overall, cutting down on major health risks. They're also more active, drinking and smoking less than their single peers. A study by Duke University, North Carolina, for example, found that people who don't marry were more than twice as likely to die early than those who had been in a stable, long-term relationship.
It improves your overall health
Being loved up has been shown to reduce the risk of all sorts of diseases, including cancers, high blood pressure, strokes and depression. Reducing your stress levels is a gift that keeps on giving too; in turn you'll also develop a much stronger immune system. Meanwhile, having sex just once a week has been linked (in a study by Wilkes University, Pennsylvania) to higher levels of immunoglobulin A, a super antibody that keeps colds and other nasty bugs at bay.
These regular bouts of lovemaking also make for a better night's sleep. The oxytocin hormone that our bodies release helps us relax. Benefits of good quality snoozing are legion, including lower weight and blood pressure and having more energy during the day - much like a healthy exercise regime.
You burn more calories
While it may not be the same as 45 minutes on the elliptical, getting it on can burn something like 100-200 calories in a half-hour session (it depends how vigorously you are going at it). Even making out for 20 minutes has the potential to burn 60 calories. It may not seem much at first glance, but doing it a few times a week really adds up - and it's a whole lot more fun than spin class.
Hugging does more than keep you warm
Who doesn't love a good hug? Making time to snuggle with your loved one has been shown to have some surprising benefits. Hugging, cuddling and even holding hands triggers the release of the 'feel-good hormone' oxytocin, and the endorphin release is similar to the feeling we get post-workout, after taking a bite of chocolate or the high that we get from orgasm.
On a deeper level, a warm embrace has been shown to lower blood pressure and help us tackle everyday stress. Luckily for us ladies, a study by the University of California a few years ago even proved that holding hands with your man has an anaesthetic effect, making us more resilient to pain. So next time you cut your finger or have a pounding headache, demand a cuddle as well as a couple of paracetamol.
Your circulation improves
It's not just his blood-flow which improves when you're together... Research shows that simply finding someone attractive - and even those first date 'butterflies' - can improve organ function. Sexual attraction has been linked to increased blood flow - proof that the opposite sex really can send our pulses racing. All that extra oxygen keeps your heart in good shape, improves focus, boosts your metabolism and even promotes glowing skin.
You look prettier
And not just because of that extra glow... There's no doubt sex can make you feel good, but it can also make you look good too. As Jerry Hall recently said in an interview, "being in love" is the top beauty tip. But it's not just celebrity hearsay - there is actual physiological evidence which supports the theory that love cuts down on the need for spot creams, blusher and even lip plumping gloss.
Our bodies produce extra oestrogen during sex, balancing hormone levels and boosting our confidence levels to produce nature's most effective acne remedy. Did we mention the shiner hair and glowing cheeks too?
And here's some more good news, sex is also known to boost collagen production, helping to keep dreaded wrinkles and dry skin at bay. As we get older our collagen production levels naturally slow - all the more reason to keep the bedroom romance alive.
You'll be cool under pressure
That pre-date adrenaline rush might put you on edge at the time, but research suggests that this acute surge of nerves is a type of 'beneficial stress' which will stand you in good stead in the long run. It's a bit like jumping out of a plane - you might be scared at the time, but you'll be glad you did it once you're feet are back on the ground.