The phrase "addicted to love" isn't as outrageous as you might think. The high levels of dopamine in your brain can cause you to feel legitimately addicted to being around your significant other. “In fact, fMRI brain scans show activity in the parietal lobes similar to activity we see when using cocaine,” Dawn Maslar, M.S., science of love expert and love biologist, tells Romper. “Falling in love can feel like being addicted to drugs.”

Maslar explains that there are several distinct phases in love, the first of which is attraction. During this phase, you might experience a queasy feeling in your stomach. “The feeling of attraction has the same response [in] your body as the fight or flight response,” she tells Romper. This can cause an upset stomach, butterflies, nerves, sweaty palms, and dilated pupils. “It’s simply your body telling you there is something you need to pay attention to,” Maslar explains. This euphoric phase is what most people think of “love at first sight,” according to behavioral scientist Clarissa Silva. It usually lasts for a few months.

If you're more forgetful and stressed when you're around your partner (or, you know, just thinking about them), this is probably due to your hormone changes. “When a person falls in love, the hormone of happiness, serotonin, ironically falls,” Maslar tells Romper, adding that it can drop to the level of someone with obsessive compulsive disorder. When this happens, a person can feel stressed and obsessed. They want to be around their partner 24/7 and feel anxious about being apart. There is also a deactivation of parts of the brain like the prefrontal cortex when a person falls in love, which can cause a selective forgetfulness of things outside the relationship. “In other words, they can know the detailed life story of their beloved but forget they have a job to go to,” Maslar explains.

If you’re looking for physical signs someone is in love with you, keep an eye out for possible sleep issues. Dr. Seuss wasn't wrong when he said, "you know you're in love when you can't fall asleep because reality is finally better than your dreams." According to Maslar, when you fall in love, the stress hormone cortisol skyrockets. The regular function of this hormone is an integral part of the sleep-wake cycle, so this increase makes it exceedingly difficult for a person to fall asleep. “In fact, you probably are pretty content to stay up all night with your beloved,” Maslar says.

Oddly enough, one study from the University of Bath noted that women tend to speak in a higher, softer voice to the person they’re interested in. It’s actually one of the more common signs of affection. “Speaking in a higher pitch is really about nurturing your partner and strengthening the bond between you both,” Silva tells Romper.

However, Maslar notes that while it’s true that a woman’s voice can become softer and higher when speaking to someone she’s interested in, researchers have also found that women will start to match their pitch with their romantic partner — so, alternately, their voices could also be getting lower. “The researchers believe that this change in voice represents a desire for affection and intimacy, and is a way of telling the other person, ‘I am one with you’,” she says.

Loss of appetite is another common "side effect" of being in love, and like forgetfulness or not being able to sleep, it goes back to the surge in hormones and brain activity. During that first stage of attraction, Maslar points out the fight or flight response can cause a loss of appetite, but once a person actually falls in love, they will get a massive hit of cortisol. “In some people, this can increase the appetite, but in others it can result in the loss of appetite,” she explains. “These lovers would rather spend their time doing other things than eating food.”

That feeling of “I’ve known you my whole life” — you know, like you’ve met the one — might be thanks to a cocktail of hormones putting in some overtime. “Oxytocin and vasopressin [are] why you may feel like you have known each other for longer than you actually have,” explains Silva. “Oxytocin, known also as the love hormone, creates calmness, produces a sense of security, and feelings of deep connection,” she says, adding that vasopressin contributes to behaviors that promote long-term planning and attachment. “The interaction of both chemicals creates a strong bond that can be perceived as having more compatibility, shared interests, and core values,” Silva tells Romper.

You might feel like the sun shines out of your partner’s behind and they are the most perfect person to walk the face of the earth. “When you fall in love, the ventromedial prefrontal cortex deactivates,” Maslar explains. “That’s the part of the brain that judges the other person.” You basically take the whole “judgment-free zone” thing a little too far. “So, no matter what they do, you think it’s cute or unique,” says Maslar.

If you feel a lot like you're on an emotional roller coaster when you're falling in love, you're not alone. “I call falling in love temporary insanity,” says Maslar. “There is a lot going on.” Which, between parts of your brain actually deactivating and your hormones having a free-for-all, is putting it mildly. “Your serotonin, the hormone of happiness, actually plummets, while your stress hormone cortisol skyrockets. The combination makes you a nervous, obsessive human being,” Maslar tells Romper.