1. You feel a genuine rush or high when you think of them
One of the most well-known scientists studying love is biological anthropologist, author, and TED Talk guru Helen Fisher. Fisher is interested in how the brain's chemistry shapes romance, and among her many interesting findings is the discovery that love and the limbic reward system are closely linked. This means that you can feel genuinely high when falling in love.
It all comes down to dopamine, a neurotransmitter that helps us feel joy. Fisher has found that the bit of our brain that creates dopamine (the Ventral Tegmental Area or VTA) is sparked by the act of falling in love: in scans you can see people's VTAs lighting up when they think about their romantic partner. Fisher went into more detail in an EliteSingles interview, but essentially the process is simple: thinking about your loved one causes your VTA to flood your body with dopamine, making you feel a rush of joy. In other words, if you suddenly feel overwhelmingly giddy and happy when you think about someone, there's a good chance you're in love.
2. You can’t get them out of your head
Brain chemistry is also responsible for the phenomenon where you just can't stop thinking about someone. This time the culprit is serotonin, another neurotransmitter. Serotonin is a mood regulator, and its presence helps us feel stable. When someone is newly in love, however, tests have shown that serotonin levels dramatically drop off – and the result is that our brains are able to go a little haywire. Without serotonin to keep an eye on proceedings, we experience the dopamine rush even more explosively, we crave it even more strongly, and we're unable to stop ourselves going back for another hit.
3. You experience sleeplessness and loss of appetite
You meet someone amazing and suddenly you're unable to eat or sleep. Sounds like a plotline from a cheesy romcom or romantic TV show, right? In fact, science tells us that these are actually real symptoms that people experience when they're first falling in love.
While love can feel great, inviting someone new into your life also requires vulnerability. Feeling vulnerable can be a little scary, so it can trigger our adrenal glands to release cortisol (aka the stress hormone) in an effort to combat the fear. One theory is that this dump of cortisol constricts the blood vessels in our stomachs, leading to a decreased appetite. An abundance of cortisol can also cause insomnia– so if that person's on your mind and you can't eat or sleep it may be time to embrace the vulnerability and admit that you're in love.
4. Your heart rates synchronize
U2 may have been on to something when they sang Two Hearts Beat as One, at least according to professors from the University of California, Davis. In a 2013 study, a UC Davis research team looked at the resting heart rates of romantic partners. They found that the heart rates of couples in love often mimicked each other, even if the couple were just sitting quietly without speaking or touching. However, this phenomenon only worked if the couple in question was romantically involved: random pairings showed no sychronicity. If your heart beats in sync with your partner's, then, it's a great sign that you're both falling in love.
5. You are more open to new ideas and activities
Feeling extra inspired to try new things (particularly those that your new squeeze likes)? Then there's a good chance that it's love. A 1995 study that tracked college students throughout the year found that those who fell in love began reporting higher levels of self esteem and increased openness to trying new ideas and diversifying their hobbies. So, if you feel compelled to start food blogging, or you develop a new found interest in your partner's hockey team, or you can't wait to try out new date ideas, it could because love has a hold on you.
6. You start planning for the future
You meet someone and soon you're daydreaming about the future: where you'll go for vacation, what your wedding will be like, how they'll look in 20 years. If the thought of all that commitment isn't scary at all, it's a great sign you're falling in love. Scientists have theorized that this sort of speculation is more than just idle daydreaming; it's part of our biological drive towards reproduction (and yes, these drives exist even in relationships where babies are not on the cards). Daydreaming about a shared future - especially if you do it with your partner - is a way of strengthening pair bonds, increasing attachment levels, and telling these biological drives to rest easy: this relationship is going to go the distance.
7. Your empathy towards your partner just keeps growing
According to Psychologist Elaine Hatfield there are two types of love: passionate and compassionate. Passionate love is that can't-keep-your-hands-off-each-other infatuation that often characterizes the early part of a relationship. Compassionate love (aka companionate love) is much softer, encompassing the growing intimacy and trust between you. And it's this second type that is most likely to last.
A big sign you're falling in compassionate love is an ever-growing empathy towards your partner: you feel sad when they're sad, happy when they're happy.10 You go out of your way for them – whether it's with a grand gesture or with something as small as bringing them their favourite ice-cream from the store. Their happiness matters to you. If you've suddenly turned into a big pool of empathy, then chances are you're truly smitten.