Shift workers are at greater risk of suffering memory problems due to their irregular patterns of eating, experts have warned.
Those who typically eat late at night can experience trouble recalling information and learning.
Midnight snacking increases the risk of altering the brain’s physiology, scientists warned.
Eating at times typically reserved for sleeping can lead to deficiencies in learning and memory, they found.
These changes occur in the hippocampal area of the brain – the area that’s linked to memory formation and storage, and emotion.
Scientists from the University of California, Los Angeles set out to investigate the cognitive effects of eating at inappropriate hours.
It was already known that such eating habits can have an impact on metabolic health – and lead to a pre-diabetic state.
Dr Dawn Loh, of the UCLA Laboratory of Circadian and Sleep Medicine, said: ‘We have provided the first evidence that taking regular meals at the wrong time of day has far-reaching effects for learning and memory.
‘Since many people find themselves working or playing during times when they’d normally be asleep, it is important to know that this could dull some of the functions of the brain.’
The researchers tested the ability of mice to recognize a novel object.
They found that mice fed during their sleep time were significantly less able to recall the object.
The scientists also subjected the mice to a fear-conditioning experiment.
They found that the mice’s long-term memory was also drastically reduced.
Both long-term memory and the ability to recognize a novel object are governed by the hippocampus, the researchers said.
The hippocampus also affects the ability to associate senses and emotional experiences with memory – and our ability to organize and store new memories.
Nerve impulses are active along specific pathways during an experience.
If we repeat the experience, the same pathways increase in strength.
But, that effect was lowered when food was made available to mice during the six-hour window in which they normally sleep – as opposed to a six-hour daytime window when the mice were active.
Certain genes involved in both the circadian clock – and learning and memory – are regulated by a cAMP response element-binding protein (or, CREB protein).
If CREB is less active, it decreases memory – and plays a role in the onset of Alzheimer’s disease.
The mice that were fed at the wrong time exhibited significantly reduced activity in CRED throughout the hippocampus.
But, the suprachiasmatic nucleus in the hypothalamus – which is the ‘master pacemaker of the circadian system’ – was unaffected.
That results in ‘desynchrony between the clocks in the different brain regions (misalignment)’ – which suggests memory impairment.
Dr Christopher Colwell, of UCLA, said: ‘Modern schedules can lead us to eat around the clock so it is important to understand how the timing of food can impact cognition.
‘For the first time, we have shown that simply adjusting the time when food is made available alters the molecular clock in the hippocampus and can alter the cognitive performance of mice.’
Though the tests were done on mice, the researchers noted that shift workers are similarly known to perform ‘less well’ on cognitive tests.
The scientists also found that eating at the wrong time disrupted sleep patterns.
Eating in the inappropriate schedule led to the loss of the normal day/night difference in the amount of sleep.
But, the total time spent asleep over 24 hours didn’t change.
Instead, sleep became fragmented.
The mice ended up catching up on sleep by grabbing short naps throughout the day and night.
The study was published in eLife.