There is a meaningful connection between emotional states, the nervous system, stress hormones, and immune function. But an important clarification is that having a negative emotion for a few hours does not “turn off” your immune system. The strongest evidence concerns persistent or repeated psychological stress and emotional distress, particularly when they disrupt sleep, behavior, cortisol regulation, or social connection.
Emotions/states most likely to impair immune function
1. Chronic stress — probably the most important
Persistent psychological stress activates the sympathetic nervous system and HPA axis, altering catecholamines and cortisol. With chronic stress, immune regulation can become abnormal, including impaired antiviral responses and excessive inflammatory signaling.
This is different from a short episode of stress, which can sometimes temporarily enhance certain immune functions.
Reference:
Dhabhar FS. Effects of stress on immune function: the good, the bad, and the beautiful. Immunologic Research. 2014;58:193–210. doi:10.1007/s12026-014-8517-0.
A more recent review describes how chronic stress can produce impaired glucocorticoid regulation and persistent inflammatory signaling.
2. Persistent anxiety/fear
Chronic anxiety keeps the body’s stress-response systems activated. Over time this can affect immune regulation, inflammatory signaling and sleep.
Reference:
Segerstrom SC, Miller GE. Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychological Bulletin. 2004;130(4):601–630. doi:10.1037/0033-2909.130.4.601.
3. Loneliness
Loneliness is particularly interesting because it isn’t simply “being alone.” It is the perception of inadequate social connection.
Research links loneliness/social isolation with altered stress physiology and inflammatory signaling, although the strength of individual associations varies between studies.
Reference:
Smith KJ, Gavey S, Riddell NE, Kontari P, Victor C. The association between loneliness, social isolation and inflammation: a systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews. 2020;112:519–541. doi:10.1016/j.neubiorev.2020.02.002.
4. Depression
Depression is associated with measurable changes in immune and inflammatory systems.
Importantly, this doesn’t mean “depression causes a weak immune system” in every person. Depression is biologically heterogeneous, and some people show more inflammatory activation than others.
Reference:
Zorrilla EP, Luborsky L, McKay JR, et al. The relationship of depression and stressors to immunological parameters: a meta-analytic review. Brain, Behavior, and Immunity. 2001;15(3):199–226. doi:10.1006/brbi.2000.0591.
Earlier meta-analytic research also found relationships between depressive affect and cellular immune measures.
5. Persistent anger/hostility
Repeated anger and hostility can repeatedly activate sympathetic stress pathways and are associated with inflammatory and cardiovascular changes.
The concern is chronic/recurrent anger, not occasionally getting angry.
Reference:
Suinn RM. Anger, anxiety, and the cardiovascular system. Journal of Clinical Psychology. 2001;57(4):495–505.
6. Chronic resentment
Resentment isn’t a uniquely measured “immune-suppressing molecule.” Rather, repetitive negative thinking, rumination and sustained physiological arousal can keep stress systems activated.
Reference:
Ottaviani C, Thayer JF, Verkuil B, et al. Physiological concomitants of perseverative cognition: a systematic review and meta-analysis. Psychological Bulletin. 2016;142(3):231–259. doi:10.1037/bul0000036.
7. Rumination
This is especially important.
You can have the original stressful event disappear while your brain continues replaying it.
Rumination/perseverative thinking can prolong physiological stress responses.
Reference:
Brosschot JF, Gerin W, Thayer JF. The perseverative cognition hypothesis: a review of worry, prolonged stress-related physiological activation, and health. Journal of Psychosomatic Research. 2006;60(2):113–124. doi:10.1016/j.jpsychores.2005.06.074.
8. Grief and prolonged bereavement
Bereavement can produce major changes in stress physiology, sleep, behavior and immune function.
Again, normal grief is not itself an immune disorder. The concern is prolonged/severe distress and its physiological consequences.
Reference:
Irwin M, Pike J, Cole JC. Effects of a behavioral intervention on immune function in elderly individuals with bereavement. Psychosomatic Medicine. 2003;65(4):592–601.
9. Hopelessness
Persistent hopelessness is associated with psychological and physiological stress and can be accompanied by unhealthy behaviors, poor sleep and social withdrawal.
Reference:
Steptoe A, Marmot M. Positive affect and health-related neuroendocrine, cardiovascular, and inflammatory processes. Proceedings of the National Academy of Sciences. 2005;102(18):6508–6512.
10. Chronic helplessness
Feeling that you have no control over important stressors can be particularly stressful.
Perceived control is an important moderator of the stress response.
Reference:
Segerstrom SC, Miller GE. Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychological Bulletin. 2004;130(4):601–630.
11. Persistent shame
Chronic shame and self-critical emotional states can contribute to stress, rumination and social withdrawal.
The evidence is stronger for chronic psychological distress as a whole than for shame independently suppressing immunity.
Reference:
Dickerson SS, Kemeny ME. Acute stressors and cortisol responses: a theoretical integration and synthesis of laboratory research. Psychological Bulletin. 2004;130(3):355–391.
12. Chronic guilt
Similar to shame, persistent guilt can become a form of repetitive negative cognition and psychological stress.
The immune evidence is indirect rather than demonstrating that guilt itself independently suppresses immune cells.
Reference:
Ottaviani C, et al. Physiological concomitants of perseverative cognition: a systematic review and meta-analysis. Psychological Bulletin. 2016;142(3):231–259.
13. Social rejection
Feeling excluded or rejected can activate physiological stress pathways.
Social adversity has been associated with increased inflammatory signaling and changes in antiviral immune processes.
Reference:
Cole SW, Hawkley LC, Arevalo JMG, et al. Social regulation of gene expression in human leukocytes. Genome Biology. 2007;8:R189.
14. Chronic insecurity
Constantly feeling unsafe or uncertain can maintain the body’s threat-response systems.
The immune consequences are generally mediated through chronic stress physiology, rather than the emotion itself directly attacking immune cells.
Reference:
McEwen BS. Protective and damaging effects of stress mediators. New England Journal of Medicine. 1998;338:171–179. doi:10.1056/NEJM199801153380307.
15. Persistent negative affect
This is the broad category encompassing sustained patterns of:
- worry
- irritability
- sadness
- fear
- anger
-
pessimism
A systematic review/meta-analysis examining psychosocial factors and influenza-vaccine response found that psychological stress was associated with poorer antibody response; high negative and low positive affect were also associated with weaker immune responses in parts of the evidence base.
Reference:
Pedersen A, Zachariae R, Bovbjerg DH. Influence of psychological stress on upper respiratory infection: a meta-analysis of prospective studies. Psychosomatic Medicine. 2010;72(8):823–832.
The opposite side is equally interesting
You asked what emotions make immunity work less. But there is an important finding:
Positive psychological states and social connection may support healthier immune regulation.
The evidence isn’t as simple as “happiness = stronger immunity,” but positive affect, social connection, optimism and psychological well-being have been associated with favorable immune and inflammatory measures in numerous studies.
For example, social relationships appear to influence both inflammatory and antiviral pathways.
Potentially favorable states include:
- feeling socially connected
- love/affection
- gratitude
- optimism
- hope
- contentment
- sense of purpose
- calm
- psychological safety
- positive engagement
The most important distinction
I would rank the evidence approximately like this:
| Emotional/psychological state | Potential immune effect |
|---|---|
|
Chronic stress |
🔴 Strong evidence |
|
Loneliness/social isolation |
🔴 Moderate evidence |
|
Persistent anxiety |
🔴 Moderate evidence |
|
Depression |
🔴 Moderate evidence |
|
Chronic sleep-disrupting distress |
🔴 Strong indirect effect |
|
Rumination/worry |
🟠 Moderate evidence |
|
Chronic anger/hostility |
🟠 Moderate evidence |
|
Bereavement/grief |
🟠 Moderate evidence |
|
Social rejection |
🟠 Moderate evidence |
|
Shame/self-criticism |
🟡 More indirect evidence |
|
Guilt |
🟡 More indirect evidence |
|
Occasional sadness |
🟢 Not meaningfully immunosuppressive |
|
Occasional anger |
🟢 Not meaningfully immunosuppressive |
|
Normal fear response |
🟢 Short-term adaptive response |
The key concept is duration.
A short-term stress response can actually be adaptive. Your sympathetic nervous system and adrenal hormones can temporarily mobilize immune cells in preparation for injury or infection.
It’s when the brain repeatedly tells the body “there is a threat and it isn’t going away” that the system can become dysregulated. Chronic stress can produce abnormal inflammatory signaling and impaired regulation rather than simply making immunity uniformly “stronger” or “weaker.”
So I would not try to eliminate anger, fear, sadness or grief. Those are normal human emotions. The more useful target is chronic unresolved stress, rumination, loneliness, poor sleep and persistent psychological distress.
And notably, the 2023 systematic review of psychosocial factors and influenza vaccination found that psychological stress had the clearest association with poorer antibody response, whereas evidence for loneliness, sleep disturbance and social support was more limited/inconsistent.
If your goal is specifically maximizing antibacterial immunity, the next useful question is not just “which emotions hurt immunity?” but “what emotional states and practices have the best evidence for increasing NK-cell activity, T-cell function, antibody production, and reducing excessive inflammation?” Those are not all the same thing.