Sometimes, just hearing the start of a certain song can bring tears to your eyes. Whether you’re at home relaxing, in the library trying to work, or in a club just trying to have a good time, there are some songs that you just can’t help but respond emotionally to, even if the song itself isn’t particularly emotional. And it’s all because, somewhere along the line, that song became irreversibly linked in your mind with a feeling, an event, a person, or an entire era of your life, and now just hearing it brings back all of the emotions associated with those memories. In some cases, this is an amazing thing: just by playing certain songs you can relive some of your best memories, or force yourself to feel the motivation needed to keep working. However, in the worst cases, you find yourself in a situation where your night is ruined because someone played a certain Harry Styles song at pres.

The majority of people I know organise their playlists by mood or vibe. Some of my friends have a nice, neat set of playlists titled ‘Sad’, ‘Happy’, ‘Motivated’, etc; others have opted for the rather more cryptic titles of  ‘highway/motel’, ‘summer fair candy floss stall’, and ‘spirito meo non opus est propositi’, which included ‘Vienna’ by Billy Joel. These titles seem to go beyond basic, recognisable emotions into a spectrum of very specific and complex feelings.

No matter how intricately you choose to set out your emotional playlists, the songs on them are usually objectively emotional songs, so they can make people feel a certain way even if it’s their first time hearing them. However, by listening to them whenever you feel a certain emotion, you strengthen your mental link between the songs and that feeling, resulting in them having a far greater effect on you than on other people. For example, when I hear a song from my ‘Motivated’ playlist, I’m affected not just by the vibes of the song, but also by the hundreds of memories of getting work done while that song plays. This leads to a very useful result: you can easily feel specific moods on command. The ‘Motivated’ playlist puts me straight into study mode; my ‘Happy’ playlist can cheer me up in any situation; and my ‘Relaxing’ playlist is my go-to when I can’t sleep.

However, as you may have guessed, this effect of the system can be extremely negative if you didn’t choose to play the song, but heard it anyway. Hearing a song from my ‘Happy’ playlist out in public would be a nice little mini-boost, but hearing a song from my ‘Sad’ playlist would be the opposite. I almost never listen to it – if I’m sad, I’d rather listen to something happy to cheer myself up – but the 9 songs on that playlist are the absolute saddest songs I’ve ever come across over the years, and I can guarantee that hearing one of them in public would immediately ruin my day. For those that do listen to sad songs to work through their feelings, the effect can be more complex than that. I decided to ask a friend about this in order to describe it accurately: she told me about a song with lyrics that related so closely to her struggles that they were frightening, and of which just the first 30 seconds were enough to make her feel hopeless. Yet she also described the song as her favourite song by that artist, and the melody as soothing and enticing. This is a clear example of the complex emotions music can evoke in people: they go beyond happy and sad into unique feelings defined by your individual struggles and thoughts.

The ability of music to evoke memories doesn’t just work with general emotions; it also works with very specific feelings attached to memorable events in your life. Have you ever listened to a song and realised that the lyrics match up quite well with something you’re experiencing? Once you’ve made that connection, it’s hard to break it. I’ve had perfectly good songs ruined for me just because I accidentally linked the lyrics – not even the whole song, just a line or two – to a certain event, and now I can’t listen to them without thinking of it. The same goes for people: if you link certain lyrics to a person in your life, and that person then leaves, that song will forever remind you of them. But of course, if that person is still in your life, or the event you’re reminded of is a positive one, this can be a good thing. Hearing a song I sang in the choir at school brings back warm memories of rehearsals; a friend tells me that Motown songs bring her back to childhood car rides up to the Lake District, during which her mum would choose the music. The experience of listening to a favourite song live at a concert or festival can result in you reliving the feeling of that moment every time you hear it. One of my friends absolutely lives for concerts, and goes to as many as she can; this has led to an accumulation of songs and albums that she has a deep connection to and can listen to whenever she wants to feel the exhilaration of those nights.

When combined into a playlist, the overall effect can be the recall of not just specific events, but entire eras of your life. As well as my mood-based playlists, I also have a playlist for each month. This makes it particularly easy to relive a certain era of my life: I can just play ‘August ‘18’ and remember exactly how it felt to be 15 years old (verdict: not as bad as I thought it would be). Some songs I used to listen to are now very far from my music taste, but I listen to them anyway for the sake of nostalgia. I remember a few times I’ve sat with friends and listened to the theme songs of TV shows we used to love as kids, just for the sake of reminiscence.

So, the magical ability of music to provoke such strong emotions and dredge up memories is both a blessing and a curse. But despite the occasional abrupt reminder of a bad memory or lost friendship, I’d say it’s a good thing. There are so many memories that I might have forgotten if they hadn’t been linked so closely to a song; every time I hear it, it strengthens those memories, and makes it less likely that they’ll be lost to time. This even applies to the bad memories: while it might not be a pleasant experience to suddenly remember something bad, it’s nice to know that everything I’ve experienced and felt is still within me somewhere, and might one day be brought back to me through music.