Scottish researchers have their sights set on uncovering the relationship between light and bipolar disorder (BD) which could ‘pave the way’ for new treatment methods, in a new study led by the University of Edinburgh’s Helios-BD groups.

The Edinburgh team will investigate how light and the body’s internal clock influence symptoms in people with bipolar disorder.

People across Scotland diagnosed with the condition are being invited to take part in research that will test their sensitivity to light at night.

The study will seek to understand if lithium – considered one of the most effective treatments for bipolar disorder – stabilises patients’ conditions by altering their response to light.

Despite being used for more than 70 years, the team says precisely how lithium acts to improve patients’ health and wellbeing is not known.

Professor Daniel Smith, project lead and Chair of Psychiatry at the University of Edinburgh’s Centre for Clinical Brain Sciences, says:

“The study will help us to understand the complex relationship between light, circadian rhythms and treatment response. The findings could have major implications for the way that we treat bipolar disorder in the future.”

Circadian rhythms are part of people’s 24-hour internal biological clock, understood to help synchronise bodily functions and behaviour with the cycles of day and night.

For example, morning light helps people feel more awake, while darkness in the evening signals the brain to make the hormone melatonin which contributes to sleepiness.

Affecting one in every 50 people in Scotland, bipolar is characterised by extreme mood swings – from periods of deep depression to manic behaviour and elated or energised moods, often punctuated by periods of ‘relative stability’ in between.

Changes in the body’s internal clock have long been thought to play a role in bipolar disorder, with a delayed peak in melatonin associated with bipolar spectrum disorders – particularly in depressive phases.

Among those living with bipolar, hospital admissions for depression have been found to peak in autumn and winter, while admissions for mania – periods of high energy and excited behaviour – are highest in spring and summer.

However, a 2022 research review found that many gaps in the evidence base remain to be addressed.

Now, the University of Edinburgh-led project seeks to address some of these gaps.

The Edinburgh team will explore if people with bipolar disorder are hypersensitive to excessive light in the evening and see whether this disrupts their body clocks and potentially increases the risk of ‘manic relapse’.

More than 100 volunteers across Scotland – both with and without a bipolar diagnosis – will participate in a sleep study.

Hormone levels will also be tested to see if melatonin is reduced among those with bipolar compared to participants with no history of the condition.

The Edinburgh researchers will also explore whether treatment with lithium is effective in preventing hypersensitivity to light and normalising the melatonin production among those with bipolar, to better understand its mechanism of action.

Inês Pote, Research Lead in the Mental Health Evidence team at Wellcome, says:

“We know lithium is an effective treatment for bipolar disorder, but this important research will help us understand if it helps patients by altering their response to light.

“This study is an example of the wider work we are supporting around ‘back translation’ - taking an existing effective approach in mental health and working backwards to understand exactly what makes it work. This information will help us refine existing mental health treatments and develop new ones.”

Funded by Wellcome, the study is being conducted in collaboration with charity Bipolar Scotland alongside partners across the UK and in Munich.

According to the research team, if successful, this project could ‘pave the way’ for a new generation of treatment approaches that are light focused. 

Janyne Laidlaw, Biopolar Scotland CEO says:

“We are delighted to support this important research and hope the findings can lead to new and improved treatments for people with bipolar disorder.

“Working alongside the University of Edinburgh has provided opportunities for our members to be part of the Lived Experience Advisory Panel, and has helped to ensure that the lived experience of people with bipolar informs the development of this project.”

Individuals aged 18 and over – both with bipolar disorder and those with no history of mental illness – are being invited to register their interest via the HELIOS-BD study website.

Read more: Adult mental health services probe begins; Psychiatrists in ‘disbelief' over cut funding; Robots could play part in combatting loneliness; New action plans signal mental health ‘reset'; Role of Mental Health Officers ‘critical’; Self-harm support strategy launched

Sign up to our bulletin for key health & social care updates straight to your inbox and you can follow healthandcare.scot on Google News