It takes a fifth-of-a-second for the euphoria-inducing chemicals to start acting on the brain when you are looking at that special someone.
That's one of the conclusions of Stephanie Ortigue, who has co-authored a review of neuroscience research on love.
The brain imaging studies of love they covered also suggested that 12 different areas of the brain are involved (Ortigue et al., 2010).
When looking or thinking about a loved one, these areas release a cocktail of neurotransmitters across the brain, including oxytocin, dopamine, vasopressin and adrenaline.
The brain gets a similar 'hit' from love as it does from a small dose of cocaine.
Of course love comes in many varieties.
One common distinction is between passionate love and the companionate kind, with the latter growing between couples over time.
This review of the research found that passionate love activates the areas of the brain involved in reward - after all we have to be motivated to overcome all the obstacles that can get in the way of love.
But it's not just about motivation: passionate love also makes us think about our body image, about how we appear socially to the other person and it makes us focus our attention.
Passionate love also had the effect of dampening down activity in areas of the brain associated with grieving, fear and anxiety.
The authors conclude: "Together, these results show that love is more than a basic emotion. Love is also a complex function including appraisals, goal-directed motivation, reward, self-representation, and body-image. Interestingly different types of love call for different brain networks that carry a broad variety of basic and complex mechanisms..." Falling in love may feel as easy as falling off a log, but your brain is working overtime ( via spring.org.uk ).