We are just beginning to understand the relationship between healthy sleep patterns and a healthy brain. Neurotrophins, like BDNF, rhythmically rise and fall with the sleep-wake cycle (Read my post on ‘Neurotrophins are brain fertilizers’ for some background!). In animal models of sleep apnea, sleep deprivation reduces BDNF and causes learning impairments (Xie Nuerobiol Dis 2010). When I think about the hospital environment, I think about one in which there is always activity (light, talking, sound) day and night; not an environment conducive to sleep. I wonder how this environment impacts recovery after a brain injury. Researchers are just beginning to investigate how sleep interruption and deprivation, such as that experienced in a hospital, influence brain plasticity after stroke and brain injury. In one study, using a rat model of stroke, researchers in Zurich (Bassetti group, Sleep 2010) showed that animals with 12 hour sleep deprivation or 3 days of interrupted sleep beginning one day after a stroke had worsening of brain damage and an increase in genes responsible for blunting growth of dendrites (the little branches that extend out to reach neighbouring neurons). This is a big concern since branching of dendrites and growth and strengthening of synaptic connections are believed to play a key role in plasticity and recovery.
Sleep is believed to be an active neurological process in which memories are solidly formed or ‘consolidated’ in the brain. At University of Montreal (Debas PNAS 2010), researchers have shown that the ability to remember a complex sequence of movements is enhanced with sleep. Researchers have also tested this phenomenon among people with stroke. They found that improvements in movement accuracy in an arm-control task were seen only in the stroke group that slept between training and the re-test (Boyd group at University of British Columbia 2009). This improvement was not seen in people without stroke or people who simply practiced the task in the morning and then in the evening (without a period of sleep). These findings suggest that good quality sleep is likely critical to relearning of movement after a brain injury (stroke, trauma, infection, bout of MS etc.). For supporters of people recovering from brain injury, think about how you can help protect that person’s sleep. The following website from Harvard Medical School details research-based approaches to enhancing sleep quality. Sweet dreams!http://healthysleep.med.harvard.edu/healthy/getting/overcoming/tips