The sun is shining, the sky’s a vivid blue and the days are longer. For many it’s a welcome change from the dreariness of British winter. But for others, summertime and the expectation of happiness that comes with it, is unbearable.

Kenneth Caldwell, 53, from Glasgow in Scotland, has lived with depression for 30 years now and says it’s always worse in the summer. “When others are enjoying the sunshine, I am walking around in a black world,” the surveyor explains. “This makes me feel 10 times worse. Others are making plans for enjoying the sunshine and I am just trying to get through each minute.

“They don’t understand, which makes me feel more isolated.”

[Read more: Depression symptoms, diagnosis and treatment explained]

A study published this week linked hotter weather to an increase in deaths by suicide in the US and Mexico. “Hotter temperatures are clearly not the only, nor the most important, risk factor for suicide,” lead author Marshall Burke, an economist at Stanford University, acknowledged. “But our findings suggest that warming can have a surprisingly large impact on suicide risk, and this matters for both our understanding of mental health as well as for what we should expect as temperatures continue to warm.”

While it’s important to remember that depression is common all-year round, the stiflingly hot temperatures can play a part in the problem. Caldwell says the recent heatwave – with temperatures reaching 35C in parts of the UK – has made his anxiety worse as the sweating mimics symptoms he has during panic attacks. The heat can also exacerbate exhaustion and add to it – sleepless nights, owed to the hot weather, will in turn impact mood.

“I see the sun shining and this just makes me realise how detached I am from happiness,” Caldwell continues. “Memories of happier times make me feel even worse.”

Masters student Beki Morgan, 29, from Kent, started experiencing anxiety and depression when she was 13 and says over the last few years she has experienced an almost “reverse seasonal affective disorder”, where her anxiety peaks during the hotter months. Despite feeling more energetic at the start of summer, the period also represents the anniversary of several major events in her life, meaning her mind wanders to a darker place.

Last summer, Morgan barely left the house because of it. “I’d often be awake at night when things were quieter, cooler and there was less of a compulsion to do anything,” she explains. “I’d then sleep during the day, which meant I could avoid speaking to people and didn’t feel the pressure to go outside. When I started to feel better towards the autumn, it felt like the summer had passed me by.”

She regrets having missed out while everyone else was having fun, but adds she simply wasn’t well enough to be doing anything else: “When the cooler weather arrived, I simply felt grateful to have survived the season.”

Jayne Hardy from charity The Blurt Foundation lives with depression and is all too aware of the challenges the hotter season brings, alongside conflicting emotions. “The summer months bring with them a sense of energy, rambunctiousness and vibrancy which can be at odds with how we feel when we’re unwell,” she explains. “Invites to BBQs, the beach, to any social gathering which we turn down can lead us to feel even lower as the photos of the event we’ve declined make their way onto social media. On the other hand, it might be that we’re isolated and not being invited to anything which can be painful and highlight the loneliness we might feel.”

For stage manager Philippa Smith-Aitchison, from Manchester, summer is a quiet time for her work-wise which leaves her twiddling her thumbs and feeling like she lacks purpose. “This year has been super difficult,” the 39-year-old, who has lived with depression for 13 years, says. “It’s much more acceptable to hunker down and stay in in the winter which can help mask a lot of the down feelings I have. It’s harder to hide those feelings in summer.”

She does acknowledge that this inability to hide her struggles can be a good thing as it has forced her to tackle the problem head on. “This is the first year I went to see my GP in preparation for feeling bad over the summer, and we came up with a bit of an action plan,” she explains. The plan involved tweaking her medication and coming up with some cheap, simple tasks and activities to do to keep her occupied but also allow her space to rest.

She adds: “I do feel there’s more out there now about Seasonal Affective Disorder (SAD) which is great. But that ‘S’ for me is summer, and that can get overlooked.”

SAD is a form of depression which people experience at a particular time of year or during a particular season. Stephen Buckley, head of information at mental health charity Mind, explains: “If you experience SAD the change in seasons will have a much greater effect on your mood and energy levels, and perhaps lead to symptoms of depression, which can have a significant impact on your day-to-day life. Most people who have SAD will be affected when the hours of daylight are shorter between December and February, however some people do experience SAD in summer.”

Common symptoms of SAD include: lacking energy, overeating, experiencing depression and/or anxiety, or a loss of interest in things. “Feelings of hopelessness, helplessness and worthlessness often mean that people avoid their friends and relatives rather than ask for help or support,” Buckley continues. “However, this is a time when they need your help and support the most.” 

Hardy says as much as people with depression should reach out for help, loved ones should also “reach in” if they know someone is struggling. They can help by being patient, by learning some more about the mental illness and not being afraid to ask questions to aid that awareness, she says.

“It’s also important to understand that we’re not being flakey, we’re not rejecting them, we’re just protecting our mental health.” Hardy recommends loved ones to invite the person with depression to a film night, dog walk or just to hang out – and if they say ‘no’, don’t stop inviting them.

Morgan says these small actions can mean the world. “I can understand how friends might be less inclined to visit someone suffering from depression at home when it’s so pleasant to be outside,” she explains. “But simply pulling a curtain, opening a window, and having a cup of tea together can make such a difference, even when it’s just for a short period of time.

“On good days, having someone to share a gentle trip to the park with can feel world-changing. With everyone else appearing to have fun, not feeling forgotten about is really valuable.”

If your feelings are impacting your day-to-day life, visit your GP who can discuss the treatments available to you. Mind has created a free downloadable guide, which can help you prepare for your first appointment.

Useful websites and helplines:

• Mind, open Monday to Friday, 9am-6pm on 0300 123 3393
• Samaritans offers a listening service which is open 24 hours a day, on 116 123 (UK and ROI – this number is FREE to call and will not appear on your phone bill.)
• The Mix is a free support service for people under 25. Call 0808 808 4994 or email: help@themix.org.uk