When we are with other people, whether it is professionally or socially, it is generally considered good manners to be agreeable, flexible and empathetic and bad manners to impose bad moods, frustrations and irritability on the people around us. We are taught to avoid mood swings and to keep our fluctuating internal barometers to ourselves – no one wants to be subjected to our emotional highs and lows; our aim should be to project equanimity at all times.

But, inevitably, there are many people who find it hard to control their moods and simple issues, like hunger, fatigue, or even an overload of sugar or alcohol, can tip them over the edge, and turn them from reasonable human beings into snappy, argumentative fight-pickers, or morose and gloomy brooders, who refuse to participate in conversation and emanate a poisonous air of dissatisfaction from the sidelines. At this point, a bad mood can easily turn someone into a killjoy, trailing a bad atmosphere, casting gloom over other people’s enjoyment.

It is alarmingly easy to become a killjoy: if you have had a bad day, or are feeling tired and irritable, your mood can very easily infect those around you. If, for example, you are sour-faced and self-righteously intent on avoiding alcohol, and all around you are throwing caution to the wind, abstention can very quickly turn into disapproval. Be aware of the effect you are having on other people: if your influence is baleful, then bale out.

While we all have good days and bad days, most of us are self-aware and self-controlled enough to detect our killjoy tendencies and try not to inflict them on our nearest and dearest. If you’re uncomfortably aware that you haven’t been at your best, or have cast something of a pall over proceedings, it might be a good idea to apologise and acknowledge any efforts other people have made to assuage your bad humour.  You could make a quick phone call or send a text that says something like “Thanks for a great evening. My apologies if I was a bit grumpy at the beginning, I was letting work get on top of me, but you all really cheered me up.” Any irritation you have caused will soon be forgotten in the face of a gracious apology and often outlining the reasons for your moodiness will garner a sympathetic response.

We all recognise that our moods can vary according to an array of factors, from hunger levels and the weather to oppressive feelings of stress or depression. If your moodiness has its roots in the serious end of this spectrum, then you really need to seek help and understanding from the people around you; otherwise, you are likely to get into a vicious circle of displaying moodiness, winding up your friends, and then feeling resentful because they have not intuited the real reason for your behaviour. Expecting the people around you to be empathetic when they have nothing but guesswork to guide them is unrealistic. Sometimes it’s only polite to give people an explanation for aberrant behaviour; you will probably be pleasantly surprised by the sympathy and support that is offered.

Moody Manipulators

Some people, however, are inveterate exploiters of their moods, using their regular plunges into melancholy, dejection or cantankerousness to manipulate the people around them. They swing wildly between conviviality and coldness, between upbeat friendliness and dour withdrawal, confusing and distressing the people closest to them. This form of emotional bullying can be highly toxic, forcing friends and partners into situations where they either feel anxious to appease or placate the moody person, or find themselves being provoked into anger and belligerence.

Here are some ways of dealing with moody manipulators:

•Opt out

If you are overwhelmed and oppressed by someone’s mood music, you do not have to endure it. At times like this, it is always a good idea to absent yourself – take a break, go out for a coffee, call another more cheerful friend. It is certainly true that other people’s bad moods can bring you down, and you need to fight against that.

•Stay calm

Remind yourself that the moodiness on display is very likely nothing to do with you and is not your responsibility – it probably has deep and complex roots. You therefore should not immediately jump to the conclusion that it’s your fault or feel bad about yourself.

•Consider expulsion

This kind of controlling behaviour is a very bad sign, and you should probably consider whether you really want to find your contentment is being dictated by another person’s moods. Remind yourself that you may well be inflicting this person and their moodiness onto other people that you really care about, and nobody will be thanking you for introducing this disruptive element into their lives.

Ask yourself why you are choosing to spend time with someone who is having such a bad effect on you and consider moving on.

•Be non-compliant

Wielding mercurial mood swings is generally a good way of manipulating people – either into doing something they don’t want to do or reducing them to a state of abject compliance. Most victims of moodiness acquiesce because it’s a way of keeping the peace, but if you refuse to give in, you might be able to break the pattern.

•Ignorance is bliss

Just ignore the mood altogether. Accept that you can’t control another person’s emotions and concentrate instead on living your own life and controlling your own feelings.

•Confront the problem

Sometimes a direct challenge of the “You’re often really irritable with me and I’d like to know why” variety can be productive. Moody manipulators want to control the situation, but they do not want their methodology to be the subject of scrutiny or discussion.