What the Research Says About Kanna, Mood and Sleep

Mood and sleep were secondary measures in a few small studies of healthy adults. Here is what was recorded, what did not move, and what has never been tested.

"What does the research say about kanna and mood?" is a fair question, and the honest answer is shorter than most websites imply. A few small trials of one extract recorded mood and sleep as side measures in healthy adults, with mixed results. This post reports what was measured, in whom, at what dose and with what limits. It does not say kanna helps anyone with anything, because the studies cannot show that.

What did studies measure about kanna and mood?

Mood was measured with standard questionnaires and diary remarks, in healthy volunteers, never as a clinical outcome. Every study used Zembrin, a standardized extract, so none speaks for other extracts or for drinks.

Two points frame everything below. First, the participants were not patients. Second, mood was rarely the main outcome, so these trials were not built to detect a mood effect. For the full list of trials see our kanna clinical studies table, which this post draws on.

What was the result in each study?

Results run from "positive changes reported" to "no change," and the weight of the evidence is closer to the second than the first.

Put simply, the one study that headlines "mood" (Chiu) did not show a significant difference on its mood scale, and three of the studies whose designs allowed a mood comparison found none or little. A 2026 review reached a similar overall verdict: mixed, with small samples [8].

What does the research say about kanna and sleep?

No study has tested kanna's effect on sleep as a main question, so the research cannot say whether kanna affects sleep.

What exists is thin. In Chiu 2014 there was no dedicated sleep instrument. Sleep was assessed through a sleep-onset item on the HAM-D and a few adverse-event checklist entries, and the paper reports a positive effect on onset of sleep on that item, with the caution that the results are "only preliminary" [3]. Interrupted sleep appeared as an adverse event in 10% of the placebo group [3]. In Nell 2013, sleep came up only in unprompted diary comments by some participants [1]. In Dimpfel 2017, which used a sleep questionnaire, no differences were found [4].

We found no study using a sleep lab, a wearable tracker or a validated sleep-quality scale as the primary outcome. A registered trial from Northumbria University lists sleep quality as a secondary outcome, but its status is unknown and we found no results [9]. If you see a claim that kanna "improves sleep," the evidence behind it is, at most, this short list of side observations.

What has not been studied?

Most of what people actually ask about. Specifically, we found no published human research on any of the following:

• kanna in people with a diagnosed mood condition, or in people taking antidepressants
• sleep measured objectively
• use for longer than three months
• kanna in a drink, or combined with kava, caffeine, L-theanine or lion's mane
• any extract other than Zembrin

The first item matters for safety. Kanna's proposed mechanism involves the serotonin system (see how kanna works), and combining serotonergic substances can be dangerous. The NIMH notes that mixing antidepressants with other drugs or supplements that affect serotonin, such as triptans or St. John's wort, can cause serotonin syndrome, a rare but life-threatening illness [10]. Talk to a doctor before using kanna with any such medicine, and read is kanna safe.

Why can't these results be generalized?

Because the studies are small, short, healthy-only and linked to the extract's owner.

• Healthy volunteers. Scores that start near the floor leave little room to improve. Chiu's HAM-D averages were about 2 at baseline [3].
• Many outcomes, few participants. Trials that test many scales will find some small P values by chance. Chiu tested nine cognitive domains and a mood scale and reported two significant cognitive results [3].
• Within-group versus between-group. The sleep-onset change in Chiu was a within-group comparison. A change from baseline in one arm is weaker evidence than a clear difference between kanna and placebo.
• Funding ties. Chiu was funded by the extract's developer and its distributor [3], and Dimpfel includes developer-affiliated authors [4].
• Self-report. Mood scales and diary notes are subjective and open to expectation effects, though the studies used placebo controls.

What does this mean for kanna drinks?

Not much directly. The studies used capsules of a specific extract at 8 to 50 mg; canned drinks list anywhere from 15 mg to 500 mg of kanna and often add other ingredients. No trial has tested what a can does to mood or sleep, and a drink's label cannot tell you that either. Our dosage guide explains the gap, and the benefits page summarizes all the research in plain English.

This page is general information, not medical advice. These statements have not been evaluated by the FDA. Kanna products are not intended to diagnose, prevent or manage any condition, including mood or sleep conditions. If you are struggling, a doctor or the 988 Suicide and Crisis Lifeline (call or text 988) can help. kannadrinks.com is published by Psilly Goose, a kanna drink maker.

References

1. Nell H, Siebert M, Chellan P, Gericke N. A randomized, double-blind, parallel-group, placebo-controlled trial of extract Sceletium tortuosum (Zembrin) in healthy adults. J Altern Complement Med 2013;19(11):898-904. PubMed
2. Terburg D, et al. Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamus. Neuropsychopharmacology 2013;38(13):2708-16. PubMed Central
3. Chiu S, et al. Proof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects. Evid Based Complement Alternat Med 2014;2014:682014. PubMed Central
4. Dimpfel W, Gericke N, Suliman S, Chiegoua Dipah GN. Effect of Zembrin on brain electrical activity in 60 older subjects after 6 weeks of daily intake. World J Neurosci 2017;7(1):140-171. SCIRP
5. Reay J, Wetherell MA, Morton E, Lillis J, Badmaev V. Sceletium tortuosum (Zembrin) ameliorates experimentally induced anxiety in healthy volunteers. Hum Psychopharmacol 2020;35(6):1-7. PubMed
6. Hoffman JR, Marcus I, Dubnov-Raz G, Gepner Y. Ergogenic effects of 8 days of Sceletium tortuosum supplementation on mood, visual tracking, and reaction in recreationally trained men and women. J Strength Cond Res 2020;34(9):2476-81. PubMed
7. Berry AR, Langley HN, Rogers RR, Benjamin CL, Williams TD, Ballmann CG. Effects of Zembrin (Sceletium tortuosum) supplementation on mood, soreness, and performance following unaccustomed resistance exercise: a pilot study. Nutraceuticals 2021;1(1):2-11. DOI
8. de Jong M, van Niekerk S, Hamman J, van der Kooy F. Mesembryanthemum tortuosum and Zembrin: mixed evidence from in vivo animal and clinical studies on their antidepressant and anxiolytic effects. Planta Med 2026;92(8):806-823. PubMed
9. ClinicalTrials.gov. NCT05471804: Psychological effects of 8 weeks supplementation with Sceletium tortuosum extract (Zembrin). ClinicalTrials.gov
10. National Institute of Mental Health. Mental health medications. nimh.nih.gov

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