Mammals including humans are more likely to suffer from short-term memory loss during the winter, a new study suggests.
Experts at the University of Bradford looked at how rats performed in memory tests when exposed to long and short ‘photoperiods’, or periods of exposure to light.
They found a ‘significant’ link between poor memory and short day length, akin to what humans experience during the winter season.
It’s possible that the results could be applicable to humans, the team say, suggesting we’re more prone to forgetfulness during long winters.
A lack of sunlight in the winter can hinder short-term memory skills in mammals including humans, according to new University of Bradford research (stock image)
SHORT-TERM MEMORY LOSS
Short-term memory loss refers to forgetting things that occurred recently, such as conversations or events.
Having short-term memory loss is a normal part of getting older but it can also be suggestive of conditions including dementia.
Long-term memory loss, meanwhile, refers to forgetting things stored in our long-term memory – like our date of birth or names of family members.
In mammals, there’s a natural explanation for the loss of short-term memory during short daylight periods, according to the experts.
‘In summer, seasonal animals tend to put on more weight, which aids with things like reproduction and preparing for winter,’ said study author Dr Gisela Helfer.
‘But during winter, when there are fewer resources around like food and also less light, the body shuts down all sorts of functions.’
For example, cognitive processes – in particular learning and memory – can be quite energy-intensive.
For their study, the researchers used something called the novel object recognition test on lab rats, which takes advantage of their natural tendency to explore novel objects.
‘Basically, rats are put into a chamber, and they are allowed to explore two objects,’ Dr Helfer told MailOnline.
‘We then give them a new object and we measure how much time they spend exploring the new object.
‘If their short-term memory is intact, they will spend more time on the new object, but rats that have an impaired memory will explore both objects equally because both objects will appear new to them.’
The study authors also gave rats in the experiments either high-fat or low-fat diets – but this didn’t change the effect of the short photoperiods.
‘Numerous studies have already shown a link between poor diet and loss of short-term memory, but this is the first time we have made a link between memory impairment and seasons,’ said study author Dr Gisela Helfer.
‘We assumed a high fat diet would have a negative impact on memory but we found that even animals with a healthy diet still performed poorly when in a short photoperiod.’
The experts used the novel object recognition test on lab rats to determine how their memory was affected by short photoperiods (stock image)
According to Dr Helfer, it’s still ‘really difficult’ to say how much the results of the experiments apply to humans.
‘It is debatable whether humans are seasonal animals,’ she said.
‘However, we know that photoperiod (day length) has an impact on animal behaviour (e.g. anxiety, depression, stress) in non-seasonal animals.’
Although further research is needed on humans, the field could lead to new treatments for a number of conditions.
‘This is a very niche area of research but one which also has massive potential,’ said Dr Helfer.
‘More research needs to be done but this could, for example, lead to the use of photoperiod therapy as a non-invasive treatment for things like seasonal affective disorder, depression, anxiety and stress.’
Light therapy – which uses artificial light that mimics natural light – can treat seasonal affective disorder (SAD) and certain other conditions by exposure to artificial light. SAD is a type of depression that occurs at a certain time each year, usually autumn or winter (stock image)
The new study, published in the journal Physiology and Behavior, follows previous research into the use of prolonged photoperiods, or ‘light therapy’, on humans.
Light therapy involves being close to a device called a ‘light therapy box’ that gives off bright light to mimic natural outdoor light.
It could become more widespread for the treatment of conditions including seasonal affective disorder (SAD), also known as ‘winter depression’.
Amazingly, previous research has shown that light therapy can improve cognitive function after traumatic brain injury in humans.
ZOOM CALLS CAN STAVE OFF MEMORY LOSS, STUDY FINDS
Regular Zoom calls can protect against dementia, according to research published in 2021.
Time spent online with loved ones, via video calls or social media, was directly related to the rate of memory loss over a 15-year period in more than 11,000 Britons aged over 50.
The researchers found it was particularly beneficial for maintaining episodic memory – the ability to recall meaningful events.
Impaired episodic memory is one of the early signs of dementia.
The study, published in Journals of Gerontology, was led by Snorri Rafnsson, associate professor of dementia care at the University of West London.
‘Learning to use online social technology can offer direct cognitive simulation to keep memory function active,’ he said.