This is the next article in our ‘Light and health’ series, where we look at how light affects our physical and mental health in sometimes surprising ways. Read other articles in the series.

It’s spring and you’ve probably noticed a change in when the Sun rises and sets. But have you also noticed a change in your mood?

We’ve known for a while that light plays a role in our wellbeing. Many of us tend to feel more positive when spring returns.

But for others, big changes in light, such as at the start of spring, can be tough. And for many, bright light at night can be a problem. Here’s what’s going on.

An ancient rhythm of light and mood

In an earlier article in our series, we learned that light shining on the back of the eye sends “timing signals” to the brain and the master clock of the circadian system. This clock coordinates our daily (circadian) rhythms.

“Clock genes” also regulate circadian rhythms. These genes control the timing of when many other genes turn on and off during the 24-hour, light-dark cycle.

But how is this all linked with our mood and mental health?

Circadian rhythms can be disrupted. This can happen if there are problems with how the body clock develops or functions, or if someone is routinely exposed to bright light at night.

When circadian disruption happens, it increases the risk of certain mental disorders. These include bipolar disorder and atypical depression (a type of depression when someone is extra sleepy and has problems with their energy and metabolism).

Light on the brain

Light may also affect circuits in the brain that control mood, as animal studies show.

There’s evidence this happens in humans. A brain-imaging study showed exposure to bright light in the daytime while inside the scanner changed the activity of a brain region involved in mood and alertness.

Another brain-imaging study found a link between daily exposure to sunlight and how the neurotransmitter (or chemical messenger) serotonin binds to receptors in the brain. We see alterations in serotonin binding in several mental disorders, including depression.

What happens when the seasons change?

Light can also affect mood and mental health as the seasons change. During autumn and winter, symptoms such as low mood and fatigue can develop. But often, once spring and summer come round, these symptoms go away. This is called “seasonality” or, when severe, “seasonal affective disorder”.

What is less well known is that for other people, the change to spring and summer (when there is more light) can also come with a change in mood and mental health. Some people experience increases in energy and the drive to be active. This is positive for some but can be seriously destabilising for others. This too is an example of seasonality.

Most people aren’t very seasonal. But for those who are, seasonality has a genetic component. Relatives of people with seasonal affective disorder are more likely to also experience seasonality.

Seasonality is also more common in conditions such as bipolar disorder. For many people with such conditions, the shift into shorter day-lengths during winter can trigger a depressive episode.

Counterintuitively, the longer day-lengths in spring and summer can also destabilise people with bipolar disorder into an “activated” state where energy and activity are in overdrive, and symptoms are harder to manage. So, seasonality can be serious.

Alexis Hutcheon, who experiences seasonality and helped write this article, told us:

[…] the season change is like preparing for battle – I never know what’s coming, and I rarely come out unscathed. I’ve experienced both hypomanic and depressive episodes triggered by the season change, but regardless of whether I’m on the ‘up’ or the ‘down’, the one constant is that I can’t sleep. To manage, I try to stick to a strict routine, tweak medication, maximise my exposure to light, and always stay tuned in to those subtle shifts in mood. It’s a time of heightened awareness and trying to stay one step ahead.

So what’s going on in the brain?

One explanation for what’s going on in the brain when mental health fluctuates with the change in seasons relates to the neurotransmitters serotonin and dopamine.

Serotonin helps regulate mood and is the target of many antidepressants. There is some evidence of seasonal changes in serotonin levels, potentially being lower in winter.

Dopamine is a neurotransmitter involved in reward, motivation and movement, and is also a target of some antidepressants. Levels of dopamine may also change with the seasons.

But the neuroscience of seasonality is a developing area and more research is needed to know what’s going on in the brain.

How about bright light at night?

We know exposure to bright light at night (for instance, if someone is up all night) can disturb someone’s circadian rhythms.

This type of circadian rhythm disturbance is associated with higher rates of symptoms including self-harm, depressive and anxiety symptoms, and lower wellbeing. It is also associated with higher rates of mental disorders, such as major depression, bipolar disorder, psychotic disorders and post-traumatic stress disorder (or PTSD).

Why is this? Bright light at night confuses and destabilises the body clock. It disrupts the rhythmic regulation of mood, cognition, appetite, metabolism and many other mental processes.

But people differ hugely in their sensitivity to light. While still a hypothesis, people who are most sensitive to light may be the most vulnerable to body clock disturbances caused by bright light at night, which then leads to a higher risk of mental health problems.

Where to from here?

Learning about light will help people better manage their mental health conditions.

By encouraging people to better align their lives to the light-dark cycle (to stabilise their body clock) we may also help prevent conditions such as depression and bipolar disorder emerging in the first place.

Healthy light behaviours – avoiding light at night and seeking light during the day – are good for everyone. But they might be especially helpful for people at risk of mental health problems. These include people with a family history of mental health problems or people who are night owls (late sleepers and late risers), who are more at risk of body clock disturbances.

Alexis Hutcheon has lived experience of a mental health condition and helped write this article.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.

Jacob Crouse, Research Fellow in Youth Mental Health, Brain and Mind Centre, University of Sydney; Emiliana Tonini, Postdoctoral Research Fellow, Brain and Mind Centre, University of Sydney, and Ian Hickie, Co-Director, Health and Policy, Brain and Mind Centre, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Oral retinoids are a type of medicine used to treat severe acne. They’re sold under the brand name Roaccutane, among others.

While oral retinoids are very effective, they can have harmful effects if taken during pregnancy. These medicines can cause miscarriages and major congenital abnormalities (harm to unborn babies) including in the brain, heart and face. At least 30% of children exposed to oral retinoids in pregnancy have severe congenital abnormalities.

Neurodevelopmental problems (in learning, reading, social skills, memory and attention) are also common.

Because of these risks, the Australasian College of Dermatologists advises oral retinoids should not be prescribed a month before or during pregnancy under any circumstances. Dermatologists are instructed to make sure a woman isn’t pregnant before starting this treatment, and discuss the risks with women of childbearing age.

But despite this, and warnings on the medicines’ packaging, pregnancies exposed to oral retinoids continue to be reported in Australia and around the world.

In a study published this month, we wanted to find out what proportion of Australian women of reproductive age were taking oral retinoids, and how many of these women were using contraception.

Our results suggest a high proportion of women are not using effective contraception while on these drugs, indicating Australia needs a strategy to reduce the risk oral retinoids pose to unborn babies.

Contraception options

Using birth control to avoid pregnancy during oral retinoid treatment is essential for women who are sexually active. Some contraception methods, however, are more reliable than others.

Long-acting-reversible contraceptives include intrauterine devices (IUDs) inserted into the womb (such as Mirena, Kyleena, or copper devices) and implants under the skin (such as Implanon). These “set and forget” methods are more than 99% effective.

The effectiveness of oral contraceptive pills among “perfect” users (following the directions, with no missed or late pills) is similarly more than 99%. But in typical users, this can fall as low as 91%.

Condoms, when used as the sole method of contraception, have higher failure rates. Their effectiveness can be as low as 82% in typical users.

Oral retinoid use over time

For our study, we analysed medicine dispensing data among women aged 15–44 from Australia’s Pharmaceutical Benefit Scheme (PBS) between 2013 and 2021.

We found the dispensing rate for oral retinoids doubled from one in every 71 women in 2013, to one in every 36 in 2021. The increase occurred across all ages but was most notable in young women.

Most women were not dispensed contraception at the same time they were using the oral retinoids. To be sure we weren’t missing any contraception that was supplied before the oral retinoids, we looked back in the data. For example, for an IUD that lasts five years, we looked back five years before the oral retinoid prescription.

Our analysis showed only one in four women provided oral retinoids were dispensed contraception simultaneously. This was even lower for 15- to 19-year-olds, where only about one in eight women who filled a prescription for oral retinoids were dispensed contraception.

A recent study found 43% of Australian year 10 and 69% of year 12 students are sexually active, so we can’t assume this younger age group largely had no need for contraception.

One limitation of our study is that it may underestimate contraception coverage, because not all contraceptive options are listed on the PBS. Those options not listed include male and female sterilisation, contraceptive rings, condoms, copper IUDs, and certain oral contraceptive pills.

But even if we presume some of the women in our study were using forms of contraception not listed on the PBS, we’re still left with a significant portion without evidence of contraception.

What are the solutions?

Other countries such as the United States and countries in Europe have pregnancy prevention programs for women taking oral retinoids. These programs include contraception requirements, risk acknowledgement forms and regular pregnancy tests. Despite these programs, unintended pregnancies among women using oral retinoids still occur in these countries.

But Australia has no official strategy for preventing pregnancies exposed to oral retinoids. Currently oral retinoids are prescribed by dermatologists, and most contraception is prescribed by GPs. Women therefore need to see two different doctors, which adds costs and burden.

Rather than a single fix, there are likely to be multiple solutions to this problem. Some dermatologists may not feel confident discussing sex or contraception with patients, so educating dermatologists about contraception is important. Education for women is equally important.

A clinical pathway is needed for reproductive-aged women to obtain both oral retinoids and effective contraception. Options may include GPs prescribing both medications, or dermatologists only prescribing oral retinoids when there’s a contraception plan already in place.

Some women may initially not be sexually active, but change their sexual behaviour while taking oral retinoids, so constant reminders and education are likely to be required.

Further, contraception access needs to be improved in Australia. Teenagers and young women in particular face barriers to accessing contraception, including costs, stigma and lack of knowledge.

Many doctors and women are doing the right thing. But every woman should have an effective contraception plan in place well before starting oral retinoids. Only if this happens can we reduce unintended pregnancies among women taking these medicines, and thereby reduce the risk of harm to unborn babies.

Dr Laura Gerhardy from NSW Health contributed to this article.

Antonia Shand, Research Fellow, Obstetrician, University of Sydney and Natasha Nassar, Professor of Paediatric and Perinatal Epidemiology and Chair in Translational Childhood Medicine, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.