Last week I was up skiing, hoping that the combination of exercise every day and exposure to bright sunlight would help with the sleep.
It turns out that everyone in the condo was tired and in bed by 10pm most nights, and I was stuck hitting the sack at that same time – about an hour and a half earlier than usual. My Zeo Sleep Monitor didn’t work so well because I was also using the same smartphone to play some isochronic tones from SleepTracks, and the two didn’t seem to cooperate all that well on a single device (at home, I have an iTouch for the music and an Android phone for the Zeo ap). I didn’t use the monitor all week.
So my reflections on how well I slept while on the ski trip are just that – reflections. Not very objective, as I am continuing to find out – see my article on nighttime perceptions of sleep. With the exception of one day, I felt pretty good the whole trip and was able to function just fine during the entire time.
While I was up there, I received an update from Yan at SleepTracks, where he ran across a study linking tart cherry juice with significantly increased levels of melatonin in the body. This led to longer and better quality sleep for the people in the study.
Tart cherry juice was previously studied for it’s muscle damage prevention properties. During this experiment, athletes being tested also talked about improved sleep with the juice, and so another pilot study was constructed to test this link.
The abstract of the study itself is here, and it sounds like good science – I’ve written before about using double-blind studies, and this one seems to cover most of the bases (highlighting is mine):
Tart Montmorency cherries have been reported to contain high levels of phytochemicals including melatonin, a molecule critical in regulating the sleep-wake cycle in humans.
The aim of our investigation was to ascertain whether ingestion of a tart cherry juice concentrate would increase the urinary melatonin levels in healthy adults and improve sleep quality.
In a randomised, double-blind, placebo-controlled, crossover design, 20 volunteers consumed either a placebo or tart cherry juice concentrate for 7 days. Measures of sleep quality recorded by actigraphy and subjective sleep questionnaires were completed. Sequential urine samples over 48 h were collected and urinary 6-sulfatoxymelatonin (major metabolite of melatonin) determined; cosinor analysis was used to determine melatonin circadian rhythm (mesor, acrophase and amplitude). In addition, total urinary melatonin content was determined over the sampled period. Trial differences were determined using a repeated measures ANOVA.
Total melatonin content was significantly elevated (P < 0.05) in the cherry juice group, whilst no differences were shown between baseline and placebo trials. There were significant increases in time in bed, total sleep time and sleep efficiency total (P < 0.05) with cherry juice supplementation. Although there was no difference in timing of the melatonin circardian rhythm, there was a trend to a higher mesor and amplitude.
These data suggest that consumption of a tart cherry juice concentrate provides an increase in exogenous melatonin that is beneficial in improving sleep duration and quality in healthy men and women and might be of benefit in managing disturbed sleep
The Problems With This Study
The only issues I really see at the outset is the sample size – 20 seems to be a small number. The findings are supported by some other small studies investigating the use of tart cherry juice, although the results were less dramatic.
The other significant problem I see is the primary reliance on a sleep diary to determine quality of the sleep. It seems to me that something more objective (if you want inexpensive, try a Zeo) would be in order.
As with all good science, though, the researchers documented their shortcomings (again, highlighting is mine):
There are a number of limitations in this pilot study. Although we powered the study to detect moderate effects on the primary outcome variables, the sample size is small. In addition, there was no polysomnographic assessment of sleep as either a screening tool or as an outcome. Participants who were not screened out by subjective report and structured interviews, but still had apnea, may have gone unidentified in this study. Between-group differences would have been mitigated by the crossover design as such participants would have served as their own controls. Polysomnography is also considered the gold standard with respect to the objective measurement of sleep. Although polysomnography is a standard assessment method in most pharmaceutical trials, it is rarely achieved in pre–post-treatment insomnia intervention trials outside of industry support. In fact, the vast majority of studies used as rational by a National Institutes of Health State of the Science Conference to recommend cognitive-behavioral therapy for insomnia as a first-line treatment for insomnia are based on subjective data.19 This is also the case in trials of depression and anxiety, where the norm is for primary outcomes to be based on subjective reports using validated instruments.
And here’s the kicker:
CherryPharm, Inc., the maker of the tart cherry juice, funded this research study in its entirety. No other competing financial interests exist.
So in the end I think it’s worthwhile to pursue. I’m a bit disturbed by the sponsorship of the study, but I believe the researchers compensated for that by admitting it up front. I can resolve the polysomnograph issue myself with my Zeo Sleep Monitor. As for the small sample size – the only sample size I really care about is me, so as long as there isn’t a big downside to taking tart cherry juice (and I can’t see that there would be one – unless the sugar content is really high) I’m going to give it a shot.
Can’t hurt – might help. Stay tuned.
UPDATE: I tried Tart Cherry out for a few weeks, and could notice no appreciable difference in sleep. The same goes for melatonin, so it’s not surprising. I say this over and over again – your mileage will vary, so give it a shot and see if it works for you!!