Vestibular symptoms are related to the proportion of REM sleep in people with sleep complaints: A preliminary report.

OBJECTIVE/BACKGROUND: Though sleep problems (apnea, insomnia) and related daytime symptoms (fatigue, anxiety, depression) have been associated with vestibular problems (falls, dizziness), it is not well known which particular sleep features relate to vestibular problems. We thus assessed symptoms of vestibular problems in patients visiting a sleep clinic and evaluated how they were associated with objective sleep parameters derived from polysomnography and relevant daytime symptoms. PATIENTS/METHODS: The polysomnography data of thirty-one patients (61% female, between 20 and 79 years of age) who were referred for clinical sleep assessment was collated with subjective measures of symptoms linked to vestibular problems (rated on the Situational Characteristics Questionnaire), as well as fatigue, anxiety and depression symptoms. Multiple linear regression was used to identify factors associated with vestibular symptoms, including analyses adjusted for age, sex, medication use and total sleep time. RESULTS: A higher percentage of REM sleep and more severe anxiety symptoms were independently associated with more severe vestibular symptoms, which survived adjusted analyses. Other sleep stages, as well as as sleep efficiency, apnea-hypopnea index and oxygen saturation were not significantly related to vestibular symptoms. CONCLUSIONS: These results point at vestibular symptoms as possible important and overlooked correlates of variations in sleep architecture in individuals with sleep complaints. Though replication is needed to confirm findings from this limited sample, the results highlight the importance of assessing vestibular symptoms in people with sleep complaints. In particular, further investigations will need to address the potential implication of REM sleep for vestibular functions and the directionality of this relation.

Different types of avoidance behavior in rats produce dissociable post-training changes in sleep.

Avoidance learning affects post-training sleep, and post-training sleep deprivation impairs performance. However, not all rats learn to make avoidance responses, and some rats fail to escape; a definitive behavior of learned helplessness, a model of depression. This study investigated the changes in sleep associated with different behaviors adopted following avoidance training. Rats (n=53) were trained for 100 trials over 2 days (50 trials/day), followed by 23-24 h of post-training polysomnography, then re-tested (25 trials). At re-test, rats were categorized into: 1) Active Avoiders (AA; n=22), 2), Non-learning (NL; n=21), or 3) Escape Failures (EF; n=10). AA rats increased avoidances over days, whereas the NL and EF groups did not. EF rats increased escape failures over days, whereas the NL and AA rats did not. EF rats had increased rapid eye movement (REM) sleep in the first 4h on training day 1. They also had increased non-REM sleep in the first 4h and last 4h on both training days. AA rats had increased REM sleep 13-20 h post-training. The type of behavioral strategy adopted throughout training is associated with a unique pattern of changes in post-training sleep. Training-dependent changes in post-acquisition sleep may reflect distinct processes involved in the consolidation of these different memory traces.