Can fish oil counteract sleep deprivation?

Dietary fish oil did not prevent sleep deprived rats from a reduction in adipose tissue adiponectin gene expression
Original source: Lipids in Health and Disease 2008, 7:43
Authors: Ana BM Mattos, Monica JS Pinto, Cristiane Oliveira, Carolina Biz, Eliane B Ribeiro, Claudia M Oller do Nascimento, Monica L Andersen, Sergio Tufik, and Lila M Oyama (corresponding author)
Publication date: 5 November 2008
DOI (digital document ID): 10.1186/1476-511X-7-43
Requires subscription? No
Publicly-available abstract: Yes

Synopsis:
Sleep deprivation has been one of the hallmarks of modern society. Where it was once limited to the elderly, now even youth are chronically sleep deprived. Sleep deprivation is linked to adverse metabolic effects, including insulin resistance. Omega-3 fatty acids found in fish oil have been seen to improve insulin sensitivity -- decrease insulin resistance. We don't yet know how this works, but researchers believe that adiponectin has a role.

The aim of this study is to assess the effects of diets high in fish oil on sleep-deprived subjects. The authors note that while in humans, sleep deprivation is associated with weight gain, sleep-deprived rats tend to lose weight. This suggests to them a method of measuring insulin resistance in such a way that it is not related to weight gain. Glucose tolerance, serum insulin, and adiponectin levels are examined in both sleep-deprived and non-sleep-deprived rats.

The rats were kept awake for 96 hours, which is when the most dramatic alterations in lipid and hormone concentrations occur. At that time, the rats were subjected to a glucose tolerance test, starting with blood drawn after a 12-hour fast, and then after the glucose was given, at time intervals of 4, 12, 20, 24, 28 and 32 minutes. The blood sampled was tested for glucose concentration, insulin, and adiponectin levels. The animals were then killed, weighed, and the fat and protein contents of their bodies separated and measured. Adiponectin and transfer-RNA were measured from the animals' adipose tissues.

Sleep deprivation caused the rats to lose weight whether or not they were on fish-oil-rich diets (this is normal for rats). Non-sleep-deprived rats did not lose weight. Sleep-deprived rats fed a normal diet lost fat; those fed a fish-oil-rich diet did not. No change was observed in protein content of any of the groups.

Following the glucose tolerance tests, glucose concentration was significantly higher in the rats allowed to sleep than those who were sleep-deprived -- and in the last measurement, the glucose level in the rats who were both sleep-deprived and fed a fish-oil-rich diet dropped even further relative to the other groups.

Serum insulin and adiponectin was similar across all groups; however, the gene expression of adiponectin in abdominal tissue was lower in the sleep-deprived rats than the non-sleep-deprived rats. Insulin levels were lower in sleep-deprived male rats, so there may have been unaccounted-for factors in the test.

The authors examine the findings of previous studies on lipid consumption, fish oil, sleep deprivation, and adiponectin expression in rats to put their study into context. They conclude that sleep deprivation does cause a stress-related drop in adiponectin gene expression, which negatively effects insulin sensitivity.


Reliability:
There were only 5-9 rats per group studied. This is a very small sample, in which results can be skewed. Rats may not be a good model for humans in this environment, as humans tend to gain weight when sleep-deprived and there are perceived correlations between weight gain and insulin sensitivity. The readings for the rats were taken at the point of peak change of a single episode of sleep deprivation, rather than after a long period of chronic sleep deprivation (e.g., 1 month at 2 hrs less sleep than normal mice get). This is the difference between students spending a couple of all-nighters cramming for an exam versus a young professional working sixteen-hour days for several years to establish himself in a competitive field.

Practical Applications:
If it could be proven that fish oil supplements (or a diet rich in fish) could protect humans against some of the adverse metabolic effects of sleep deprivation, then this could be an effective and inexpensive treatment against those medical risks.

This synopsis was based on the entire article.