A melatonin diffuser may be good for stress and anxiety, but the jury is still out. While it may not be the main reason people take melatonin, a few studies suggest it may also have a calming effect and help reduce anxiety, along with helping you fall asleep.
A 2020 review from the National Institutes of Health found that melatonin was effective in helping relieve anxiety in patients undergoing surgery, while a 2017 study echoed those findings for people following acute coronary syndrome (a heart attack, for example). Finally, two 2018 studies found that melatonin was more effective than popular anti-anxiety medications oxazepam and alprazolam in relieving anxiety among people having surgery.
While these studies weren’t about the effects of using a melatonin diffuser specifically, they do speak to melatonin’s ability to possibly help calm anxiety.