Lifestyle & immune function: the impact of sleep & stress management

Our daily lives can be hectic, with all the demands of work, family, and social commitments. These are all essential dimensions of our lives to stay mentally and emotionally healthy, yet we also need to be in good health to keep up with it all. Two important lifestyle factors—sleep and stress—must be considered when it comes to overall health and wellbeing. We explore how each of these impacts our immune system and the ways we can manage them.

Although our bodies don't seem physically active while we sleep, many internal processes keep our immune system working well In fact, a 2023 study conducted by the University of Bergen found that sleeping well may reduce one's vulnerability to infections.They found that patients who slept less than six hours a night were 27% more likely to have an infection, while those who slept more than nine hours were 44% less likely to report one.

The study builds on existing research that shows the link between poor sleep and reduced immune function. The Sleep Foundation describes how this is related to how sleep can disrupt immune function. For example, in someone who has had poor sleep, inflammation levels during the night persist upon waking, whereas for someone who has had a good night’s sleep, their inflammation levels return to normal levels before waking up.

While inflammation is a normal response to fighting infection or illness, according to Novant Health, persistent inflammation can damage healthy cells and lead to poor health.

Improves function of immune T cells

• T cells help fight infection in our body. One study found that a drop in stress hormones during sleep improved contact between T cells and virus-infected cells.
• The findings indicate that those who have poor sleep, with elevated levels of stress hormones, may have lower functioning of T cells for killing pathogens.

Increases production of cytokines to fight infection

• During sleep, the immune system releases proteins called cytokines, which target infection and inflammation, according to the University of Cincinatti. Lack of sleep may lead to decreased production of these cytokines, antibodies, and cells that fight infection.
• One study found that restricting sleep to 4 hours for one night led to the generation of inflammatory cytokines, which signal other cells to promote inflammation.

With these negative impacts of poor sleep on the immune system, it is important to prioritise it. Experts agree that seven to nine hours is generally a healthy amount of sleep.

Relaxing sleep routine:

• Having a relaxing routine in place is key. You can start it as the day draws to a close, after chores, dinner, and other activities are done, so you can prepare to wind down your body physically and mentally, transitioning it to rest. This can include light stretching, listening to relaxing music, diffusing essential oils, meditation, or whatever feels calming to you.

Write a "to do" list for the next day:

• If there are things "to do" that keep lingering in your mind which are keeping you up, perhaps write a list of these with the intention that you will set yourself to do these the first thing in the morning after having had a good night's rest.  

Peaceful sleep environment:

• Setting up a relaxing sleep environment also plays an important role in helping you achieve better sleep. This includes switching off devices, dimming the lights, and ensuring a clutter-free bedroom.

Not only is stress unavoidable in life, but it can also be necessary to help us achieve, ensure we are alert, and stay on top of things. Let's look at what happens to the immune system when stress strikes.As one research paper describes, when we experience a short burst of stress, the fight-or-flight mode is activated, during which certain cells are released into the bloodstream to prepare for potential injury or infection. This short-term stress increases levels of pro-inflammatory cytokines, and the hormone cortisol is also secreted during this time to limit the inflammation.

However, when the stress becomes longer-term and chronic, it results in higher cortisol levels in the body for too long. This is related to higher levels of pro-inflammatory cytokines. In addition, chronic stress decreases white blood cells that help fight infection. According to the Cleveland Clinic, lower lymphocyte levels are associated with a higher risk for viruses, such as the common cold. Stress can also lead to problems sleeping, creating a vicious cycle as sleep can lead to higher susceptibility to stress.

Our body's ability to adapt to and defend against stress is primarily affected by how much we look after our body in terms of what we feed it, how much we exercise it and how much social support we have to support our mental health during times of stress.

Healthy diet:

• Eating a healthy diet with a variety of whole foods can help ensure your body is getting the vitamins and minerals needed for the body to function well enough to be resilient against stress and its effects.

Exercise:

• Exercise can also be a great stress buster as it reduces stress hormones of cortisol and adrenaline while producing feel-good brain chemicals called endorphins that help elevate mood.

Social support:

• Having social support to turn to when you are experiencing a stressful time can help alleviate emotional stress and loneliness. Studies have found that social support can also improve resilience to stressful situations.