The study, “Functional connectome mediates the association between sleep disturbance and mental health in preadolescence: A longitudinal mediation study,” was published January 18 and aimed to understand how two separate brain networks interconnect as it relates to sleep deprivation and mental health.
The study acknowledges that sleep disturbance is known to be associated with various mental disorders and often precedes the onset of mental disorders in youth.
“Given the increasingly acknowledged bidirectional influence between sleep disturbance and mental disorders, we aim to identify a shared neural mechanism that underlies sleep disturbance and mental disorders in preadolescents,” researchers said.
Ze Wang, an associate professor of diagnostic radiology and nuclear medicine at the University of Maryland School of Medicine, is the study’s author.
Wang told Newsweek that he noticed the importance of sleep many years ago when he read several papers about the immediate amyloid protein deposition in the brain after a short-term sleep deprivation.
Amyloid is the neurotoxic waste in the brain and needs to be transported out by cerebrospinal fluid, which is most often static. The best time to have more cerebrospinal fluid and increased flow rate, Wang said, is at night when lying down to fall asleep due to a reduced cerebral blood flow.
“From my personal experience, I noticed the big difference after I sleep well and started to think [of] a scientific project,” he told Newsweek. “If I lack a good sleep, my brain is basically a mess and I can not continuously think and can not remember things I just read.
“Because of these strong scientific interests, I have been looking for an opportunity to investigate the sleep effects on the brain. The opportunity came when I got access to the large ABCD data three years ago.”
That was when he gained access to Adolescent Brain Cognitive Development (ABCD) data, which provides large data to the research community to test novel hypotheses about brain and behavior development, as well as early signatures or alterations that are linked to mental health.
The ABCD study, which officially launched in 2016, is said to be the largest long-term study of brain development and child health in the U.S. Funded by the National Institutes of Health, the study includes 21 research sites across the country where approximately 11,878 children ages 9-10 years participate.
Researchers track biological and behavioral development through adolescence into young adulthood, using different technological measures to dissect an array of data—sports, video games, social media, unhealthy sleep patterns and smoking—and learn how such childhood experiences affect a child’s changing brain, as well as social, behavioral, academic and health-based outcomes.
“The data is so big that it took me and my lab members two months to download them, about several months to fully process them,” Wang told Newsweek. “My initial plan was to examine sleep effects on brain activity in terms of the dynamic change of the acquired brain signal and on the inter-regional connection. I’m also interested in the mediation effects [of] other contributing factors, such as puberty and socioeconomic status.”
He and his fellow researchers found that out of 186 unique connectivity measures tested, the effect of sleep disturbance and mental disorders converged in two brain networks: One is the dorsal attention network, mainly responsible for attention, memory and inhibition control; the other is the default mode network, shown to have an important role for facilitating general brain function.
Data for 9,350 children was analyzed for this specific study, with one-year follow-ups completed for 8,845 children.
“Our work identified robust relationships between sleep disturbance, mental health and functional connectivity of many brain networks,” researchers said. “Total sleep disturbance and mental problems both impacted similar network connectivities and their relationship was mediated by these identified network connectivities.”
Wang said that except for a few cases, weakened connections are related to worse mental health and more sleep disturbance. Also, connections between these networks “significantly modulated the relationship between mental health and sleep quality.”
In other words, he said both the brain and the behavior should be considered into the same model when researching any mental problems—even if it remains unclear why sleep and mental health are connected in these separate brain networks.
According to Wang, the findings that have previously been addressed before include: how a lack of sleep in teens is associated with altered connections between and within two important brain networks; that sleep deficits are associated with more mental problems, and this correlation is bidirectional and is mediated through the brain connections within and through the two networks; and that the associations and mediation effects can last at least a year, according to the data.
“Teenagers are getting less and less sleep because of all kinds of excitations and tech advances for producing more feasible and more attractive visual systems,” Wang said. “Unfortunately, this is with consequences. One possible consequence is the harm to mental health, which may reciprocally impact sleep quality and start a worse-to-worse cycle. Another possible consequence is the change of brain connections. These consequences may last for a long time.”
He added that due to the adolescent brain still being under rapid development, sustained sleep deficits may lead to permanent impairment to the brain and to cognitive functions.
“Getting good sleep back is crucial to teens’ brain and mental health,” he said. “While our findings may cause worry if the sleep patterns are too difficult to change, there are alternative approaches.”
He mentioned noninvasive cognitive therapy as an example to improve brain function connectivities that are associated with sleep disturbance and mental health.
The study’s authors said future research may include examining the effectiveness of regulating connectivity strength between the dorsal attention network and the default mode network to induce “positive behavioral change related to mental health and sleep problems.”
“We have several ongoing studies planned to unveil the causal effects of sleep deficits on mental health and to study the longitudinal changes of these findings and other hypothesized effects in a larger time scale, for example, three years or five years or more,” Wang told Newsweek.
