Does gratitude or optimism help your health and longevity?

Gratitude interventions, such as keeping a gratitude journal, are the more studied of the two. Three randomised trials show that consciously focusing on gratitude increases positive feelings and overall well-being compared with a control condition. That effect on positive affect is the most robust finding; effects on other outcomes, such as physical complaints, were mixed¹.

In working adults, eight of nine randomised trials found a reduction in perceived stress and depressive symptoms following gratitude exercises. There is, however, an important nuance: interventions with four or fewer exercises showed no significant effect, and the effects on well-being were inconsistent. The high variability between studies makes it difficult to draw firm conclusions².

Sleep quality is the most consistent physical outcome: five of the eight studies that measured sleep found an improvement in people who practised gratitude exercises. At the same time, most of those studies had methodological limitations, so this result needs confirmation in better-designed trials³. For measurable physical outcomes such as blood pressure and inflammatory markers, the evidence is plainly too sparse and too inconsistent for any conclusion: there are typically one or two studies per outcome, with conflicting results³.

Gratitude journalling is also used in workplace programmes for healthcare professionals. Broader programmes showed improvements in well-being and burnout, but gratitude was always combined with other components. The independent effect of the journal is therefore impossible to separate from the rest of the programme^4,5.

There is considerably less to say about optimism on the basis of the available studies. A conceptual analysis describes optimism as a personality trait associated with well-being and health, but that is an observational link, not evidence that training optimism improves health. Causal conclusions cannot be drawn from this type of analysis⁶. In short: gratitude exercises have a reasonably well-supported effect on mood and possibly sleep, but for optimism as a health intervention, clinical evidence is currently entirely lacking.