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.

Exposure to light is crucial for our physical and mental health, as this and future articles in the series will show.

But the timing of that light exposure is also crucial. This tells our body to wake up in the morning, when to poo and the time of day to best focus or be alert. When we’re exposed to light also controls our body temperature, blood pressure and even chemical reactions in our body.

But how does our body know when it’s time to do all this? And what’s light got to do with it?

What is the body clock, actually?

One of the key roles of light is to re-set our body clock, also known as the circadian clock. This works like an internal oscillator, similar to an actual clock, ticking away as you read this article.

But rather than ticking you can hear, the body clock is a network of genes and proteins that regulate each other. This network sends signals to organs via hormones and the nervous system. These complex loops of interactions and communications have a rhythm of about 24 hours.

In fact, we don’t have one clock, we have trillions of body clocks throughout the body. The central clock is in the hypothalamus region of the brain, and each cell in every organ has its own. These clocks work in concert to help us adapt to the daily cycle of light and dark, aligning our body’s functions with the time of day.

However, our body clock is not precise and works to a rhythm of about 24 hours (24 hours 30 minutes on average). So every morning, the central clock needs to be reset, signalling the start of a new day. This is why light is so important.

The central clock is directly connected to light-sensing cells in our retinas (the back of the eye). This daily re-setting of the body clock with morning light is essential for ensuring our body works well, in sync with our environment.

In parallel, when we eat food also plays a role in re-setting the body clock, but this time the clock in organs other than the brain, such as the liver, kidneys or the gut.

So it’s easy to see how our daily routines are closely linked with our body clocks. And in turn, our body clocks shape how our body works at set times of the day.

What time of day?

Let’s take a closer look at sleep

The naturally occurring brain hormone melatonin is linked to our central clock and makes us feel sleepy at certain times of day. When it’s light, our body stops making melatonin (its production is inhibited) and we are alert. Closer to bedtime, the hormone is made, then secreted, making us feel drowsy.

Our sleep is also partly controlled by our genes, which are part of our central clock. These genes influence our chronotype – whether we are a “lark” (early riser), “night owl” (late sleeper) or a “dove” (somewhere in between).

But exposure to light at night when we are supposed to be sleeping can have harmful effects. Even dim light from light pollution can impair our heart rate and how we metabolise sugar (glucose), may lead to psychiatric disorders such as depression, anxiety and bipolar disorder, and increases the overall risk of premature death.

The main reason for these harmful effects is that light “at the wrong time” disturbs the body clock, and these effects are more pronounced for “night owls”.

This “misaligned” exposure to light is also connected to the detrimental health effects we often see in people who work night shifts, such as an increased risk of cancer, diabetes and heart disease.

How about the gut?

Digestion also follows a circadian rhythm. Muscles in the colon that help move waste are more active during the day and slow down at night.

The most significant increase in colon movement starts at 6.30am. This is one of the reasons why most people feel the urge to poo in the early morning rather than at night.

The gut’s day-night rhythm is a direct result of the action of the gut’s own clock and the central clock (which synchronises the gut with the rest of the body). It’s also influenced by when we eat.

How about focusing?

Our body clock also helps control our attention and alertness levels by changing how our brain functions at certain times of day. Attention and alertness levels improve in the afternoon and evening but dip during the night and early morning.

Those fluctuations impact performance and can lead to decreased productivity and an increased risk of errors and accidents during the less-alert hours.

So it’s important to perform certain tasks that require our attention at certain times of day. That includes driving. In fact, disruption of the circadian clock at the start of daylight savings – when our body hasn’t had a chance to adapt to the clocks changing – increases the risk of a car accident, particularly in the morning.

What else does our body clock control?

Our body clock influences many other aspects of our biology, including:

• physical performance by controlling the activity of our muscles
• blood pressure by controlling the system of hormones involved in regulating our blood volume and blood vessels
• body temperature by controlling our metabolism and our level of physical activity
• how our body handles drugs and toxins by controlling enzymes involved in how the liver and kidneys eliminate these substances from the body.

Morning light is important

But what does this all mean for us? Exposure to light, especially in the morning, is crucial for synchronising our circadian clock and bodily functions.

As well as setting us up for a good night’s sleep, increased morning light exposure benefits our mental health and reduces the risk of obesity. So boosting our exposure to morning light – for example, by going for a walk, or having breakfast outside – can directly benefit our mental and metabolic health.

However, there are other aspects about which we have less control, including the genes that control our body clock.

Frederic Gachon, Associate Professor, Physiology of Circadian Rhythms, Institute for Molecular Bioscience, The University of Queensland and Benjamin Weger, NHMRC Emerging Leadership Fellow Institute for Molecular Bioscience, The University of Queensland

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

The way people living with dementia experience the world can change as the disease progresses. Their sense of reality or place in time can become distorted, which can cause agitation and distress.

One of the best ways to support people experiencing changes in perception and behaviour is to manage their environment. This can have profound benefits including reducing the need for sedatives.

One such strategy is the use of dolls as comfort aids.

What is ‘doll therapy’?

More appropriately referred to as “child representation”, lifelike dolls (also known as empathy dolls) can provide comfort for some people with dementia.

Memories from the distant past are often more salient than more recent events in dementia. This means that past experiences of parenthood and caring for young children may feel more “real” to a person with dementia than where they are now.

Hallucinations or delusions may also occur, where a person hears a baby crying or fears they have lost their baby.

Providing a doll can be a tangible way of reducing distress without invalidating the experience of the person with dementia.

Some people believe the doll is real

A recent case involving an aged care nurse mistreating a dementia patient’s therapy doll highlights the importance of appropriate training and support for care workers in this area.

For those who do become attached to a therapeutic doll, they will treat the doll as a real baby needing care and may therefore have a profound emotional response if the doll is mishandled.

It’s important to be guided by the person with dementia and only act as if it’s a real baby if the person themselves believes that is the case.

What does the evidence say about their use?

Evidence shows the use of empathy dolls may help reduce agitation and anxiety and improve overall quality of life in people living with dementia.

Child representation therapy falls under the banner of non-pharmacological approaches to dementia care. More specifically, the attachment to the doll may act as a form of reminiscence therapy, which involves using prompts to reconnect with past experiences.

Interacting with the dolls may also act as a form of sensory stimulation, where the person with dementia may gain comfort from touching and holding the doll. Sensory stimulation may support emotional well-being and aid commnication.

However, not all people living with dementia will respond to an empathy doll.

The introduction of a therapeutic doll needs to be done in conjunction with careful observation and consideration of the person’s background.

Empathy dolls may be inappropriate or less effective for those who have not previously cared for children or who may have experienced past birth trauma or the loss of a child.

Be guided by the person with dementia and how they respond to the doll.

Are there downsides?

The approach has attracted some controversy. It has been suggested that child representation therapy “infantilises” people living with dementia and may increase negative stigma.

Further, the attachment may become so strong that the person with dementia will become upset if someone else picks the doll up. This may create some difficulties in the presence of grandchildren or when cleaning the doll.

The introduction of child representation therapy may also require additional staff training and time. Non-pharmacological interventions such as child representation, however, have been shown to be cost-effective.

Could robots be the future?

The use of more interactive empathy dolls and pet-like robots is also gaining popularity.

While robots have been shown to be feasible and acceptable in dementia care, there remains some contention about their benefits.

While some studies have shown positive outcomes, including reduced agitation, others show no improvement in cognition, behaviour or quality of life among people with dementia.

Advances in artificial intelligence are also being used to help support people living with dementia and inform the community.

Viv and Friends, for example, are AI companions who appear on a screen and can interact with the person with dementia in real time. The AI character Viv has dementia and was co-created with women living with dementia using verbatim scripts of their words, insights and experiences. While Viv can share her experience of living with dementia, she can also be programmed to talk about common interests, such as gardening.

These companions are currently being trialled in some residential aged care facilities and to help educate people on the lived experience of dementia.

How should you respond to your loved one’s empathy doll?

While child representation can be a useful adjunct in dementia care, it requires sensitivity and appropriate consideration of the person’s needs.

People living with dementia may not perceive the social world the same way as a person without dementia. But a person living with dementia is not a child and should never be treated as one.

Ensure all family, friends and care workers are informed about the attachment to the empathy doll to help avoid unintentionally causing distress from inappropriate handling of the doll.

If using an interactive doll, ensure spare batteries are on hand.

Finally, it is important to reassess the attachment over time as the person’s response to the empathy doll may change.

Nikki-Anne Wilson, Postdoctoral Research Fellow, Neuroscience Research Australia (NeuRA), UNSW Sydney

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