Some studies have found an association between poor sleep quality (especially in midlife) and an increased risk of dementia. Alzheimer’s Society says that once dementia has developed, those with the condition may slip into a vicious sleep cycle too ― “A person with dementia may have problems with sleeping well or at the right times. Poor sleep may make the symptoms of dementia worse,” they say.Now, a new study has linked daytime sleepiness to an increased risk of dementia, though it does not prove napping in the day causes the condition.How did the study work?A new study published in the journal Neurology looked at questionnaire results from 445 participants, all of whom were over 65.The average age was 76; none of them had dementia at the start of the study. They were asked about a range of sleep disturbances, including getting up in the middle of the night, struggling to fall asleep in the first place, having trouble with sleep temperature, and any sleep medications. Researchers also asked whether the participants felt sleep