White matter hyperintensity and cognitive impairments in chronic insomniacs

Abnormal sleep architecture and white matter hyperintensities (WMHs) may be involved in cognitive impairment. There is little evidence on the connections between WMHs and chronic insomnia disorder (CID). Therefore, we evaluated the severity of WMHs and polysomnography parameters as well as cognitive tests to explore the underlying connections. There was no significant difference in sex, age, or educational attainment (years) between the two groups. The data showed significant decreases in total sleep time, sleep efficiency, and percentage of time spent in stage nonrapid eye movement sleep 3 in the CID group, but this group also showed prolonged sleep latency and increased percentages of time spent in stages nonrapid eye movement sleep 1 and nonrapid eye movement sleep 2 and wake after sleep onset. Moreover, chronic insomniacs showed poor performance on the attention, intelligence, and memory tests, as well as visual recognition and visual regeneration. Importantly, WMHs were observed to be associated with sleep latency, percentage of time spent in stage nonrapid eye movement sleep 1, and percentage of time spent in stage nonrapid eye movement sleep 3. In conclusion, our findings suggest that there are certain underlying correlations between WMHs and sleep architecture. Abnormal sleep architecture and WMHs could be involved in the impairment of cognitive function in CID. However, it remains unclear whether WMHs are a pre-existing abnormality or a consequence of CID.