Could Insomnia Be Weakening My Immune System? September 4, 2026 Could Insomnia Be Weakening My Immune System? If you regularly struggle to get a good night’s sleep, you’ve probably noticed how drained you can feel the next day. But the effects of poor sleep may go deeper than low energy. Sleep and the immune system are closely connected, and ongoing insomnia may interfere with your body’s ability to defend itself against illness. Your immune system is your body’s defence network - It helps fight infections, heal wounds and protect you from disease. Getting enough high-quality sleep gives this system the time and conditions it needs to work effectively. What happens to your immune system while you sleep? Sleep might look like a period of inactivity, but behind the scenes, your immune system is surprisingly busy. During sleep, the activity of certain immune cells and proteins changes. This includes cytokines, which act as chemical messengers that help coordinate your immune response.1 Sleep also appears to strengthen ‘immune memory’, helping your immune system recognise and respond to potentially harmful substances it has encountered before.1 This nightly activity supports both innate immunities, your body’s broad first line of defence, and adaptive immunity, which develops targeted responses to specific threats.1 Can poor sleep make you more likely to get sick? Research suggests it can. People who regularly sleep fewer than six or seven hours a night have been found to have a higher risk of infections.2 One reason may be that ongoing sleep loss disrupts the careful balance of inflammation in the body.1 In healthy sleep, inflammatory activity increases during the night before returning towards normal as morning approaches. When you consistently don’t get enough sleep, this process can be disrupted, potentially allowing low-level inflammation to persist.1 Sleep may even affect your vaccine response Sleep doesn’t just help your body fight infections. It may also influence how effectively your immune system learns to recognise them. Studies examining vaccines have found that insufficient sleep can result in a weaker immune response.1 Adults who regularly get fewer than seven hours of sleep may not give their bodies enough opportunity to develop strong immunological memory after vaccination. The relationship works both ways Sleep supports immunity, but your immune system can also change how you sleep. Think about the last time you had a bad cold or flu. Feeling exhausted and wanting to spend more time in bed is part of the body’s response to infection.1 During illness, changes in immune activity can promote deeper sleep, which may allow the body to redirect more energy towards fighting the infection.1 This helps explain why rest can feel so important when you’re unwell. Make healthy sleep a priority A consistent sleep schedule, a comfortable sleeping environment and limiting phones and tablets in bed can all support better sleep. Relaxation techniques may also help. If insomnia is persistent or severe, or you find yourself experiencing recurring illnesses alongside poor sleep, speak with your doctor. Taking your sleep seriously is an important part of supporting your immune system and your overall health. References 1. Suni, Eric, and Kimberly Truong. “How Sleep Affects Immunity.” Sleep Foundation, 15 Aug. 2023, https://www.sleepfoundation.org/physical-health/how-sleep-affects-immunity. Accessed 11 Aug. 2026. 2. Prather, Aric A., et al. “Behaviorally Assessed Sleep and Susceptibility to the Common Cold.” Sleep, vol. 38, no. 9, Sept. 2015, pp. 1353–59, https://doi.org/10.5665/sleep.4968.
