There’s been a lot of debate over whether Week 5 blues are a self-perpetuating myth or not. Are we just persuading ourselves that we feel worse because we expect to – and are we ignoring serious mental health concerns by giving them such a title? Whatever your opinion on the topic might be, you probably haven’t thought that much about the name. What is it about the colour blue that has led us to associate it with feeling down?

To be or look blue has been in dictionaries since as early as 1785, when it appeared in A Classical Dictionary of the Vulgar Tongue along with the definition “to be confounded, terrified, or disappointed”. Although we have this early evidence of the phrase in use, it is a lot more difficult to pin down where it comes from. Early usage suggests it may be linked to illness and pallor. Corpses tend to be pale, and might even be a little blue-tinged, so the colour blue has long been associated with ill health. If someone is badly bruised, we might describe them as ‘black and blue’, demonstrating another way in which to be blue wouldn’t be very fun. It is entirely possible that to feel blue simply comes from this.

If you have as little agricultural experience as I do, you probably don’t know that wheat can become ‘blue-moulded’ if it isn’t threshed properly. Threshing grain traditionally involves beating it against the floor, and if the grain isn’t beaten sufficiently or isn’t dry enough, it can become bruised in the process and discoloured, leading to the name ‘blue-moulded’. We might all be describing ourselves as pieces of wheat when we say that we’re feeling blue, as one suggestion is that our idiom comes from blue-moulded grain.

Another theory hinges on a link between blue and divine anger. According to myth, if Zeus, the Ancient Greek god of the sky and thunder, was annoyed or upset, he would make rain. Though rain is not literally blue, it is often depicted as being blue, and some thinkers have suggested that it was Zeus’ blue rain of anger that led to the colour being associated with unhappiness. This explanation would certainly predate the 1785 dictionary entry, but is perhaps a little spurious.

One suggestion that makes a lot of sense but sadly doesn’t work chronologically is that the phrase came from blues music, which often involves telling a sad story. Unfortunately, the first copyrighted blues composition comes from 1912, rather a lot later than the dictionary. It is more likely that the blues got its name from the same source as the phrase feeling blue, though the origins are just as unclear in this context.

“Before ‘feeling blue’ became a phrase, people talked a lot about ‘blue devils’, which were feelings of sadness”

As per usual in a case of uncertain etymology, there is a naval theory to be put forward. Once upon a time, if a ship lost a captain or another important officer while it was out at sea, the custom was to fly blue flags while returning to port. Ships would also often have a blue stripe painted along the hull to mark the loss of the sailor. This meant that the colour blue came to be linked with the death of important figures and was a sign of mourning, and so might have led to a description of oneself as feeling a similar way. It appears, however, that this was used in such a specific context that it would be difficult for it to have become a widespread phrase, and while the two do seem to be connected, this naval practice probably didn’t give rise to our idiom.

Word Up: Five words whose meanings have completely changed

In fact, it is probably the case that alcohol is to blame for our describing ourselves as blue. Before ‘feeling blue’ became a phrase, people talked a lot about ‘blue devils’, which were feelings of sadness, and is a phrase that has been recorded since the 1600s. It originally referred to hallucinations brought on by alcohol withdrawal, and the idea is that if you were bad enough to be seeing them, you probably weren’t feeling too great. Over time, the ‘devils’ part of the phrase was dropped, and it lost its direct link to alcohol and came instead to mean a generally grim feeling. Blue is still associated with alcohol today – the phrase ‘blue law’, for example, which is a law preventing alcohol from being sold, comes from the meaning of ‘blues’ as drinking alcohol. ‘Blue devils’ is both an old and a common enough phrase to be a plausible origin for ‘feeling blue’, and so it’s most likely – though not definite – that our idiom comes from this.

So, after looking at gods, grains, and boats, it turns out it all goes back to alcohol and hangovers in the end. However you choose to take care of yourself as Week 5 rushes towards us, you can reassure yourself that drowning your sorrows is totally authentic, right?