Studies of n-3 PUFAs deficiency in experimental animals have revealed a number of mechanisms through which DHA might specifically affect sleep regulation, including impaired functioning of the superchiasmatic nuclei, altered melatonin release, and disruption to endocannabinoid signaling. In humans, higher maternal levels of DHA appear to be linked to more mature infant sleep patterns while lower levels of DHA have been negatively associated with parent ratings of children’s sleep disturbance.
Results from an exploratory pilot trial in children (n = 43, age 7–9 years) indicated that supplementation with DHA might improve objectively measured sleep. However, no studies evaluated the effects of EPA, which might also be relevant, given the previously observed effects of n-3 PUFAs on serotonin release and the production of prostaglandins which is known to mediate the sleep/wake cycle.
The present study investigated the effects of 26 weeks’ supplementation with oils rich in either DHA or EPA on subjective and objective sleep quality in 84 healthy, adult, low consumers of oily fish, using a randomized, placebo-controlled, double-blind, parallel groups design.
The results suggest a beneficial role of n-3 PUFAs, particularly DHA, for sleep. Benefits include an overall increase in sleep efficiency and a reduction in sleep latency, although these positive objective measures were not consistent with subjective ratings following DHA-rich oil.
The report states: “This study was the first to demonstrate some positive effects of dietary supplementation with n-3 PUFAs in healthy adult normal sleepers, and provides novel evidence showing the differential effects of n-3 PUFA supplements rich in either DHA or EPA.”
Participants were randomly assigned to receive one of three treatments for 26 weeks (placebo, DHA-rich oil, EPA-rich oil).
Before the baseline and week 26 assessments, participants were required to visit Northumbria University’s Brain, Performance, and Nutrition Research Centre to collect an actiwatch, sleep diary, and urine sampling pack. Participants were required to wear the actiwatch and complete the sleep diary for the 7 nights prior to the baseline and week 26 assessments and to provide urine samples the night before and the morning of the baseline and week 26 assessments. Participants were asked to avoid alcohol and refrain from intake of ‘over the counter’ medications for 24 hours and caffeine for 18 hours before the baseline and week 26 assessments.
Participants also reported to the centre during week 13 to complete the Leeds Sleep Evaluation Questionnaire (LSEQ) and subjective awakening scales.
Mechanisms of action
The observed results suggest that supplementation with DHA-rich oil in healthy adults who do not habitually consume oily fish, resulted in a significant increase in sleep efficiency and a significant decrease in sleep latency compared to placebo.
However, the report notes that despite these improvements in the objective actigraphy sleep measures in the DHA-rich group, it was also found that this group reported feeling less rested compared to placebo, and less energetic and ready to perform than those given EPA-rich oil.
The results also suggest specific roles of DHA and EPA in sleep. The report notes: “The shortened sleep times identified within the current study, following the EPA-rich oil as compared to the DHA-rich oil, might potentially be explained by the role of EPA inhibiting the formation of E2-series prostaglandins, which in turn inhibit the release of serotonin.
“As serotonin promotes wakefulness and inhibits REM sleep, it might be that increased levels of circulating EPA indirectly upregulate the promotion of wakefulness, resulting in decreased sleep time. It should be noted that although participants in the EPA-rich oil group reported the shortest sleep times, this did not appear to lead to any reduction in the quality of sleep.
“In fact, a trend towards a significant increase in sleep efficiency, compared to placebo, was observed along with no increases in the time spent awake, number of awakenings, or decreased ratings of subjective sleep quality. This might potentially suggest that EPA is beneficial for regulating a healthy sleep cycle and could help protect against suboptimal sleep. Further investigations into the relationship between n-3 PUFAs and the serotonin/melatonin synthesis pathway and effects on sleep architecture are required.”
Jackson. P. A., et al
“Differential Effects of DHA- and EPA-Rich Oils on Sleep in Healthy Young Adults: A Randomized Controlled Trial”