Late snackers, beware: night-time eating may be dulling our brains

Eating late at night can cause a deficiency in the type of learning and memory controlled by the hippocampal area of the brain, according to research published in the journal eLife.

The researchers, from the Semel Institute at the University of California, say that although their findings have not been confirmed in humans (the research was carried out on mice) there is evidence that shift workers perform less well on cognitive tests.

Dawn Loh, the study’s lead author, 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 effects of irregular eating habits on metabolic health are well established, but this study aimed to uncover the cognitive effects of eating at inappropriate times.

The researchers tested the ability of mice to recognise a novel object. Mice fed during their sleep time were significantly less able to recall the object. Long-term memory was also dramatically reduced, which was demonstrated during a fear conditioning experiment.

These functions are controlled by the hippocampus, which plays an important role in our ability to associate senses and emotional experiences with memory. In the mice fed at the wrong time, the total activity throughout the hippocampus was significantly reduced, with the strongest effects in the day.

Professor Christopher Colwell from the Department of Psychiatry and Biobehavioral Sciences at 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 cogitation.

‘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.’

The researchers also noticed that inappropriate eating times caused the mice to have interrupted sleep patterns, as they had to take more short naps throughout the day and night.