Michelle Carr

Effects of a Tart Cherry Juice Beverage on the Sleep of Older Adults with Insomnia: A Pilot Study

This study ascertained whether a proprietary tart cherry juice blend (CherryPharm, Inc., Geneva, NY, USA) associated with anecdotal reports of sleep enhancement improves subjective reports of insomnia compared to a placebo beverage. The pilot study used a randomized, double-blind, crossover design where each participant received both treatment and placebo for 2 weeks with an intervening 2-week washout period. Sleep continuity (sleep onset, wake after sleep onset, total sleep time, and sleep efficiency) was assessed by 2-week mean values from daily sleep diaries and disease severity by the Insomnia Severity Index in a cohort of 15 older adults with chronic insomnia who were otherwise healthy. The tart cherry juice beverage was associated with statistically significant pre- to post-treatment improvements on all sleep variables. When compared to placebo, the study beverage produced significant reductions in insomnia severity (minutes awake after sleep onset); no such improvements were observed for sleep latency, total sleep time, or sleep efficiency compared to placebo. Effect sizes were moderate and in some cases negligible. The results of this pilot study suggest that CherryPharm, a tart cherry juice blend, has modest beneficial effects on sleep in older adults with insomnia with effect sizes equal to or exceeding those observed in studies of valerian and in some, but not all, studies of melatonin, the two most studied natural products for insomnia. These effects, however, were considerably less than those for evidence-based treatments of insomnia: hypnotic agents and cognitive-behavioral therapies for insomnia.

Morning rapid eye movement sleep naps facilitate broad access to emotional semantic networks.

STUDY OBJECTIVES The goal of the study was to assess semantic priming to emotion and nonemotion cue words using a novel measure of associational breadth for participants who either took rapid eye movement (REM) or nonrapid eye movement (NREM) naps or who remained awake; assess relation of priming to REM sleep consolidation and REM sleep inertia effects. DESIGN The associational breadth task was applied in both a priming condition, where cue-words were signaled to be memorized prior to sleep (primed), and a nonpriming condition, where cue words were not memorized (nonprimed). Cue words were either emotional (positive, negative) or nonemotional. Participants were randomly assigned to either an awake (WAKE) or a sleep condition, which was subsequently split into NREM or REM groups depending on stage at awakening. SETTING Hospital-based sleep laboratory. PARTICIPANTS Fifty-eight healthy participants (22 male) ages 18 to 35 y (Mage = 23.3 ± 4.08 y). MEASUREMENTS AND RESULTS The REM group scored higher than the NREM or WAKE groups on primed, but not nonprimed emotional cue words; the effect was stronger for positive than for negative cue words. However, REM time and percent correlated negatively with degree of emotional priming. Priming occurred for REM awakenings but not for NREM awakenings, even when the latter sleep episodes contained some REM sleep. CONCLUSIONS Associational breadth may be selectively consolidated during REM sleep for stimuli that have been tagged as important for future memory retrieval. That priming decreased with REM time and was higher only for REM sleep awakenings is consistent with two explanatory REM sleep processes: REM sleep consolidation serving emotional downregulation and REM sleep inertia.

Infrequent dream recall associated with low performance but high overnight improvement on mirror‐tracing

Although sleep facilitates learning and memory, the roles of dreaming and habitual levels of recalling dreams remain unknown. This study examined if performance and overnight improvement on a rapid eye movement sleep‐sensitive visuomotor task is associated differentially with habitually high or low dream recall frequency. As a relation between dream production and visuospatial skills has been demonstrated previously, one possibility is that frequency of dream recall will be linked to performance on visuomotor tasks such as the Mirror Tracing Task. We expected that habitually low dream recallers would perform more poorly on the Mirror Tracing Task than would high recallers and would show less task improvement following a night of sleep. Fifteen low and 20 high dream recallers slept one night each in the laboratory and performed the Mirror Tracing Task before and after sleep. Low recallers had overall worse baseline performance but a greater evening‐to‐morning improvement than did high recallers. Greater improvements in completion time in low recallers were associated with Stage 2 rather than rapid eye movement sleep. Findings support the separate notions that dreaming is related to visuomotor processes and that different levels of visuomotor skill engage different sleep‐ and dream‐related consolidation mechanisms.

Daydreams and nap dreams: Content comparisons.

Differences between nighttime REM and NREM dreams are well-established but only rarely are daytime REM and NREM nap dreams compared with each other or with daydreams. Fifty-one participants took daytime naps (with REM or NREM awakenings) and provided both waking daydream and nap dream reports. They also provided ratings of their bizarreness, sensory experience, and emotion intensity. Recall rates for REM (96%) and NREM (89%) naps were elevated compared to typical recall rates for nighttime dreams (80% and 43% respectively), suggesting an enhanced circadian influence. All attribute ratings were higher for REM than for NREM dreams, replicating findings for nighttime dreams. Compared with daydreams, NREM dreams had lower ratings for emotional intensity and sensory experience while REM dreams had higher ratings for bizarreness and sensory experience. Results support using daytime naps in dream research and suggest that there occurs selective enhancement and inhibition of specific dream attributes by REM, NREM and waking state mechanisms.

Nightmare sufferers show atypical emotional semantic associations and prolonged REM sleep-dependent emotional priming

STUDY OBJECTIVES The objective of this study was to investigate whether nightmare (NM) sufferers exhibit an abnormal network of emotional semantic associations as measured by a recently developed, rapid eye movement (REM) sleep-sensitive, associational breadth (AB) task. DESIGN NM sufferers were compared to healthy controls (CTL) for their performance on an emotional AB task containing positive and negative cue words both before and after a nap with REM sleep. AB was assessed in both a priming condition, where cue words were explicitly memorized before sleep, and a non-priming condition, where cue words were not memorized. Performance was assessed again 1 week later. SETTING The study was conducted in a sleep laboratory with polysomnographic recording at the Hôpital du Sacré-Coeur de Montréal PARTICIPANTS Twenty-eight participants between the ages of 18 and 35 years (Mage = 23.3 ± 3.4) were included in the study. MEASUREMENTS AND RESULTS The NM group scored higher than the CTL group on both positive and negative AB, with group differences persisting at the 1-week retest. However, the two groups did not differ as expected in the AB priming effect following REM sleep. Both groups showed decreased REM sleep-related AB priming for negative cue words and increased AB priming for positive cue words. However, the NM group maintained these effects 1 week later, whereas the CTL group did not. CONCLUSIONS NM sufferers may access broader than normal emotional semantic networks in the wake state, a difference that may lead to this group being perceived as more creative. The fact that the AB priming effect is maintained at the 1-week retest for NM sufferers suggests that the presence of frequent NMs may alter REM sleep-dependent emotional processes over time.

Elevated perseveration errors on a verbal fluency task in frequent nightmare recallers: a replication

A recent study reported that individuals recalling frequent idiopathic nightmares (NM) produced more perseveration errors on a verbal fluency task than did control participants (CTL), while not differing in overall verbal fluency. Elevated scores on perseveration errors, an index of executive dysfunction, suggest a cognitive inhibitory control deficit in NM participants. The present study sought to replicate these results using a French‐speaking cohort and French language verbal fluency tasks. A phonetic verbal fluency task using three stimulus letters (P, R, V) and a semantic verbal fluency task using two stimulus categories (female and male French first names) were administered to 23 participants with frequent recall of NM (≥2 NM per week, mean age = 24.4 ± 4.0 years), and to 16 CTL participants with few recalled NM (≤ 1 NM per month, mean age = 24.5 ± 3.8 years). All participants were French‐speaking since birth and self‐declared to be in good mental and physical health apart from their NM. As expected, groups did not differ in overall verbal fluency, i.e. total number of correct words produced in response to stimulus letters or categories (P = 0.97). Furthermore, groups exhibited a difference in fluency perseveration errors, with the NM group having higher perseveration than the CTL group (P = 0.03, Cohens d = 0.745). This replication suggests that frequent NM recallers have executive inhibitory dysfunction during a cognitive association task and supports a neurocognitive model which posits fronto‐limbic impairment as a neural correlate of disturbed dreaming.

It was just a dream

Exploiting our ability to lucid dream could help erase real-life traumas, finds sleep researcher Michelle Carr