There’s a strong connection between sleep and immune function—something many have noticed after just a few sleepless nights. Whether it’s from caring for sick kids or traveling across time zones, skipping out on rest often seems to invite illness.
Science backs this up. Research consistently shows that people who sleep six hours or less per night tend to have a weakened immune response. One study from the University of Washington Sleep Center found that in identical twins, the sibling who slept less was more likely to get sick. According to lead researcher Dr. Nathaniel Watson, seven or more hours of sleep is ideal for optimal immune health.
Sleep plays a crucial role in nearly every part of the immune system. It helps regulate inflammation, strengthens the body’s first line of defense, and even improves the ability to respond to vaccines. When sleep is lacking, the body’s white blood cells—key players in the innate immune system—don’t function as effectively.
The Innate Immune System and Sleep
The innate immune system acts quickly to defend the body from pathogens. But sleep deprivation reduces the effectiveness of this defense. In one study, people who slept fewer than six hours per night were four times more likely to catch a cold compared to those who got more than seven hours.
White blood cells, which form the backbone of this early defense, are among the immune components most affected by poor sleep. Without adequate rest, their ability to neutralize threats weakens, making the body more vulnerable to infection.
T Cell Activation
T cells are another critical part of immune function, helping to target and destroy infected cells—especially those invaded by viruses like influenza or even cancerous cells. In a study comparing people who had a full night’s rest to those who stayed awake, the well-rested group showed stronger T cell activation.
Stress hormones like cortisol tend to rise with sleep loss, and these hormones interfere with T cell activity. This explains why chronic stress and poor sleep often go hand-in-hand with a weaker immune response.
Cytokines, Inflammation, and Immune Balance
The immune system relies on a network of chemical messengers called cytokines. These proteins help coordinate the body’s response to infection, inflammation, and stress. Sleep boosts the production of helpful cytokines, but sleep deprivation slows this down—leaving the body more vulnerable.
Some cytokines are pro-inflammatory, and their levels tend to rise with poor sleep. Infections like severe flu or COVID-19 can trigger a runaway inflammatory response known as a cytokine storm. This overreaction can cause serious damage to tissues and organs. Adequate sleep helps keep the immune system in check, reducing the risk of excessive inflammation.
Melatonin, the body’s natural sleep hormone, plays a role too. It helps regulate the sleep-wake cycle and has powerful antioxidant effects that support immune function. Deep sleep helps reduce stress hormones, lower inflammation markers like CRP, and support a balanced immune response.
The Sleep–Immunity Connection
Regularly getting fewer than five hours of sleep is linked to higher all-cause mortality, along with increased risks for depression, infections, weight gain, and metabolic issues. Unfortunately, studies from the CDC show that over one-third of American adults don’t get enough rest.
Aiming for at least seven hours of quality sleep per night can go a long way in improving immune health, lowering inflammation, and supporting overall well-being.
Tips for Better Sleep and Immune Support
-
Stick to a consistent sleep schedule, even on weekends
-
Avoid caffeine late in the day
-
Minimize alcohol and heavy meals before bed
-
Get sunlight exposure during the day
-
Exercise regularly, but avoid intense workouts close to bedtime
-
Create a relaxing bedtime routine—meditation can help
-
Put away screens at least 30–60 minutes before sleep
If sleep is still a struggle, a natural melatonin supplement may be helpful. And for a calming bedtime ritual, a warm turmeric “golden latte” can help ease the mind, promote relaxation, and support restful sleep. Better sleep means better immune function—and a healthier, more energized body overall.
