Insomnia appears to be a long-term side-effect of stroke and this may have major consequences for recovery, a new study has found.

According to the findings, stroke patients can experience ongoing insomnia, which can reduce their ability to re-learn key skills. It can also increase their risk of depression.

While sleep problems have long been reported in people who have suffered a stroke, until now, little was known about the overall impact of this. Researchers from the UK, Germany and Switzerland decided to investigate further.

They carried out an experiment in a sleep laboratory to compare the brain signals of patients who were at least one year post-stroke, with the brain signals of the general population.

They used a polysomnogram (PSG) test, to assess the participants' brains' sleeping patterns over two nights.

The study found that stroke patients took longer to fall asleep and had poorer sleep efficiency than those who did not have a stroke. Sleep efficiency is the ratio of the total time spent asleep in a night compared to the total amount of time spent in bed. For example, if someone spends eight hours in bed, but only sleeps for four of those hours, their sleep efficiency for that night would be 50%.

The study also found that stroke patients were less likely to fall asleep during the day to compensate for lost sleep at night.

Further tests found that they were more prone to errors than the general population, increasing their risk of cognitive problems.

"Our research shows that those who have suffered from stroke maintain difficulties with their sleep, which is likely to affect their overall recovery and quality of life. The importance of sleep in aiding the recovery of patients should not be underestimated in helping to improve and maintain physical and mental wellbeing," commented Prof Annette Sterr of the University of Surrey in the UK.

She noted that sleep is not currently considered when it comes to stroke rehabilitation, but she hopes this change in the future.

"Harnessing the power of good sleep is likely to maximise recovery and quality of life," Prof Sterr added.

Details of these findings are published in the journal, Scientific Reports.