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.

Most people with knee osteoarthritis can control their pain and improve their mobility without surgery, according to updated treatment guidelines from the Australian Commission on Safety and Quality in Health Care.

So what is knee osteoarthritis and what are the best ways to manage it?

More than 2 million Australians have osteoarthritis

Osteoarthritis is the most common joint disease, affecting 2.1 million Australians. It costs the economy A$4.3 billion each year.

Osteoarthritis commonly affects the knees, but can also affect the hips, spine, hands and feet. It impacts the whole joint including bone, cartilage, ligaments and muscles.

Most people with osteoarthritis have persistent pain and find it difficult to perform simple daily tasks, such as walking and climbing stairs.

Is it caused by ‘wear and tear’?

Knee osteoarthritis is most likely to affect older people, those who are overweight or obese, and those with previous knee injuries. But contrary to popular belief, knee osteoarthritis is not caused by “wear and tear”.

Research shows the degree of structural wear and tear visible in the knee joint on an X-ray does not correlate with the level of pain or disability a person experiences. Some people have a low degree of structural wear and tear and very bad symptoms, while others have a high degree of structural wear and tear and minimal symptoms. So X-rays are not required to diagnose knee osteoarthritis or guide treatment decisions.

Telling people they have wear and tear can make them worried about their condition and afraid of damaging their joint. It can also encourage them to try invasive and potentially unnecessary treatments such as surgery. We have shown this in people with osteoarthritis, and other common pain conditions such as back and shoulder pain.

This has led to a global call for a change in the way we think and communicate about osteoarthritis.

What’s the best way to manage osteoarthritis?

Non-surgical treatments work well for most people with osteoarthritis, regardless of their age or the severity of their symptoms. These include education and self-management, exercise and physical activity, weight management and nutrition, and certain pain medicines.

Education is important to dispel misconceptions about knee osteoarthritis. This includes information about what osteoarthritis is, how it is diagnosed, its prognosis, and the most effective ways to self-manage symptoms.

Health professionals who use positive and reassuring language can improve people’s knowledge and beliefs about osteoarthritis and its management.

Many people believe that exercise and physical activity will cause further damage to their joint. But it’s safe and can reduce pain and disability. Exercise has fewer side effects than commonly used pain medicines such as paracetamol and anti-inflammatories and can prevent or delay the need for joint replacement surgery in the future.

Many types of exercise are effective for knee osteoarthritis, such as strength training, aerobic exercises like walking or cycling, Yoga and Tai chi. So you can do whatever type of exercise best suits you.

Increasing general physical activity is also important, such as taking more steps throughout the day and reducing sedentary time.

Weight management is important for those who are overweight or obese. Weight loss can reduce knee pain and disability, particularly when combined with exercise. Losing as little as 5–10% of your body weight can be beneficial.

Pain medicines should not replace treatments such as exercise and weight management but can be used alongside these treatments to help manage pain. Recommended medicines include paracetamol and non-steroidal anti-inflammatory drugs.

Opioids are not recommended. The risk of harm outweighs any potential benefits.

What about surgery?

People with knee osteoarthritis commonly undergo two types of surgery: knee arthroscopy and knee replacement.

Knee arthroscopy is a type of keyhole surgery used to remove or repair damaged pieces of bone or cartilage that are thought to cause pain.

However, high-quality research has shown arthroscopy is not effective. Arthroscopy should therefore not be used in the management of knee osteoarthritis.

Joint replacement involves replacing the joint surfaces with artificial parts. In 2021–22, 53,500 Australians had a knee replacement for their osteoarthritis.

Joint replacement is often seen as being inevitable and “necessary”. But most people can effectively manage their symptoms through exercise, physical activity and weight management.

The new guidelines (known as “care standard”) recommend joint replacement surgery only be considered for those with severe symptoms who have already tried non-surgical treatments.

I have knee osteoarthritis. What should I do?

The care standard links to free evidence-based resources to support people with osteoarthritis. These include:

• education, such as a decision aid and four-week online course
• self-directed online exercise and yoga programs
• weight management support
• pain management strategies, such as MyJointPain and painTRAINER.

If you have osteoarthritis, you can use the care standard to inform discussions with your health-care provider, and to make informed decisions about your care.

Belinda Lawford, Postdoctoral research fellow in physiotherapy, The University of Melbourne; Giovanni E. Ferreira, NHMRC Emerging Leader Research Fellow, Institute of Musculoskeletal Health, University of Sydney; Joshua Zadro, NHMRC Emerging Leader Research Fellow, Sydney Musculoskeletal Health, University of Sydney, and Rana Hinman, Professor in Physiotherapy, The University of Melbourne

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