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Does Fish Oil and Omega 3 Fat Make You Sleep Better or Worse?

by Dale Cudmore | Updated: May 20, 2023

Fish oil appears to have many health benefits, including preventing coronary heart disease (1).

The main factor behind the health benefits of fish oil are omega 3 fats, and there are some researchers that have spent time looking at if omega 3 fats could also affect sleep quality.

This post is a short review of all the relevant research I could find on fish oil and sleep.

Can Fish Oil Supplements Cause Insomnia?

I’ve seen a few anecdotes from people saying they suspect that fish oil supplements are making their sleep worse.

There’s very little research that shows a negative effect on sleep from fish oil supplementation.

However, one doctor published a case study of a single patient who had insomnia and anxiety while taking fish oil supplements (2). Once they stopped taking the fish oil supplements, the anxiety and insomnia went away.

You really can’t draw much from a single report like that, the anxiety and insomnia could have even just been a placebo effect in the first place.

However, it’s enough to say that it’s not impossible for fish oil supplements to cause sleep trouble.

It’s also possible that the particular supplement that the patient was taking was rancid (expired) or just low quality and contained problem filler ingredients.

SummaryWhile it might be possible for fish oil supplements to cause insomnia symptoms, there’s very little research to support that.

Does Fish Oil Improve Sleep Quality?

Most research actually seems to find that omega 3 fats improve sleep quality. Let’s go over a few of those studies here.

First, researchers measured fish consumption (along with other attributes) in a fishing village (3). They found:

Oily fish consumption is associated with better sleep quality. Even in people who ingest more than the recommended amount of fish, an increase in fish intake is associated with further improvement in the quality of sleep.

Keep in mind that this was a fishing village. Even the people who didn’t eat as much fish and had sleep issues still had a higher omega 3 consumption than the average Westerner today.

The Effect of Omega 3 Fats on Anxiety and Depression

Anxiety and depression are 2 of the most common causes of insomnia.

Some research focuses on not only the effect of omega 3 fats on sleep quality, but also on anxiety and depression.

The results are promising, but mixed.

First, a team of researchers conducted a double-blind study with a placebo group (4). They found that insomnia severity, depression symptoms, and anxiety all improved in the omega 3 supplement group.

The chart above shows that the insomnia severity also decreased in the placebo group, which shows how impactful the placebo effect can really be.

Another study found that omega 3 supplementation lowered inflammation and anxiety, but did not produce a significant change in depressive symptoms (5).

Omega 3 Supplements and Sleep Apnea

While it’s controversial whether or not sleep apnea is a risk factor for insomnia, it’s still a condition that lowers sleep quality and worth mentioning here.

One study found that after controlling for most variables (age, sex, race, etc.), the concentration of DHA levels (the main type of omega 3 fat in fish) was inversely related with sleep apnea severity (6).

In other words, the more DHA subjects had, the better their sleep apnea was.

SummaryWhile more research is still needed, most current studies show that omega 3 fats (typically from fish oil) improve sleep quality, and even other health markers like anxiety.

The Effect of Omega 3 Fats on Sleep Deprivation

Regardless of its effect on sleep quality, it’s still important to get enough omega 3 fats in your diet whether through fish, supplementation, or plant based sources like flaxseed.

On top of benefits like preventing heart disease, research shows that omega 3 fats may also have protective effects against sleep deprivation.

An animal study found that omega 3 supplementation nearly eliminated the negative effects of sleep deprivation on short term memory (7).

The graph below shows one of the notable results, where “SD” is the control sleep deprived group and “Omega-3/SD” is the sleep deprived group that had extra omega 3 fats.

That’s just a single animal study so you can’t draw much from it, but it’s an interesting area for further research in human subjects.

Fish Oil vs. Omega 3 Supplements

One final question you might have is whether or not you need to get omega 3 fats from fish, fish oil supplements, or omega 3 supplements derived from other sources (e.g. flax or seaweed).

Ultimately the amount of DHA and EPA is the most important factor. These are the 2 most usable forms in the body. Fish oil is mainly composed of these, while plant sources are mainly ALA (which the body converts to the other 2 at a relatively poor rate). Plant sources are better than nothing, but fish oil is typically considered higher quality.

One other factor to consider is that eating too much fish can be bad because of its mercury content. One study suggests that fish oil supplements are safer than eating more fish (8):

SummaryFish such as swordfish and shark are also a source of exposure to the heavy metal toxin, mercury. The fish oil brands examined in this manuscript have negligible amounts of mercury and may provide a safer alternative to fish consumption.

Summary: Are Omega 3 Fats Good or Bad for Insomnia?

Other than in rare cases, having more omega 3 fats in your diet appears to be beneficial for sleep quality.

While more research is still needed, the studies we looked at show that omega 3 fats consistently have a positive effect on sleep quality, insomnia severity, and anxiety.

They may even have some positive effect on depressive symptoms.


  1. Fish Oil for Primary and Secondary Prevention of Coronary Heart Disease
  2. Insomnia and exacerbation of anxiety associated with high-EPA fish oil supplements after successful treatment of depression
  3. Dietary fish intake and sleep quality: a population-based study
  4. Influence of adjuvant omega-3-polyunsaturated fatty acids on depression, sleep, and emotion regulation among outpatients with major depressive disorders
  5. Omega-3 supplementation lowers inflammation and anxiety in medical students
  6. Membrane Level of Omega-3 Docosahexaenoic Acid Is Associated with Severity of Obstructive Sleep Apnea
  7. Omega-3 fatty acids protects against chronic sleep-deprivation induced memory impairment
  8. Measurement of mercury levels in concentrated over-the-counter fish oil preparations: is fish oil healthier than fish?

Medical Disclaimer: The information on is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.

About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.