Does fish oil help with sleep? What the research does and doesn't show

The evidence doesn't support fish oil as a sleep aid for adults, at any dose. The only systematic review on the topic pooled 12 randomized trials and 8 longitudinal studies and found no effect on adults' sleep duration, latency, efficiency, quality or insomnia severity — the benefits it did find showed up only in infants and children.

What the evidence doesn't support

It doesn't support omega-3 or fish oil supplements as something that helps adults fall asleep faster, sleep longer, sleep more efficiently, or feel their sleep was better quality. It also doesn't support omega-3 as a treatment for insomnia specifically — no trial in the review below tested it against a diagnosed insomnia population. The one positive signal in the same body of research was in infants and children, a different population entirely from an adult searching for a sleep aid.

What the trials found

A 2021 systematic review and meta-analysis in Nutrition Reviews searched five databases through November 2019 and combined 20 studies — 12 randomized controlled trials and 8 longitudinal studies — on omega-3 long-chain polyunsaturated fatty acid intake and sleep-related outcomes. In infants, omega-3 reduced the percentage of active (light) sleep and the percentage of sleep-wake transitions, and increased the percentage of wakefulness, with no change to quiet sleep. In children already flagged with clinical-level sleep problems, omega-3 reduced a total sleep disturbance score; in healthy children without existing sleep problems, it changed nothing measured. In adults — the population most people searching for a fish oil sleep aid actually are — the review reported no effect on total sleep duration, sleep latency, sleep efficiency, sleep quality, or insomnia severity in any of the pooled trials.

Doses and forms of omega-3 varied across the studies pooled, and the review didn't isolate one dose as more or less effective in adults, because no adult effect was found to isolate a dose for. The authors' own conclusion was that omega-3 "may improve certain aspects of sleep health throughout childhood," with no equivalent claim made for adults, and called for more robust trials.

A separate, smaller trial in the same body of literature looked at omega-3 supplements in menopausal women and found no difference in insomnia severity or sleep quality between omega-3 and placebo, though it did find a reduction in night-sweat frequency and severity — a different mechanism (vasomotor symptoms) from a direct effect on sleep itself.

Questions people ask

Can fish oil help you sleep?

Not based on the trials available. In adults, the one systematic review pooling this research found no effect on total sleep duration, sleep latency, sleep efficiency, sleep quality or insomnia severity from omega-3 supplementation, in any of the trials it reviewed.

Does fish oil help you sleep if you're a child?

The same review found some benefit in infants' sleep organization and in children already flagged with clinical-level sleep problems, but no effect on total sleep duration in otherwise healthy children. This page is written for adults; supplement use in children is a conversation for a pediatrician, not a dosing decision made from search results.

Can fish oil disrupt or worsen sleep?

The review didn't report omega-3 worsening any adult sleep measure either. The honest summary for adults is a flat result in both directions — no benefit found, no harm found, across the trials measured.

Is there a right time of day to take fish oil for sleep?

Because no adult trial found a sleep effect to begin with, there's no timing finding to report here. Fish oil is generally taken with a meal for absorption and tolerability, a separate question from when it might help sleep.

When to talk to a doctor

Trouble falling or staying asleep that is new, persistent, or paired with daytime symptoms like loud snoring or gasping for air is worth raising with a doctor rather than working around with a supplement. Fish oil is not a treatment for insomnia or any other sleep disorder, and nothing in the evidence above supports using it in place of an evaluation. If you take medication, or are pregnant or nursing, talk to a doctor before adding any supplement.

Related reading: fish oil benefits: what the research does and doesn't show, how much fish oil should you take a day, best time to take fish oil, and fish oil and anxiety: what the research does and doesn't show.