Brain scans of people who say they have insomnia have shown differences in brain function compared with people who get a full night’s sleep.
Researchers at the University of California, San Diego, said the poor sleepers struggled to focus part of their brain in memory tests.
Other experts said that the brain’s wiring may actually be affecting perceptions of sleep quality.
The findings were published in the journal Sleep.
People with insomnia struggle to sleep at night, but it also has consequences during the day such as delayed reaction times and memory.