Poor sleep and inflammation: how lack of sleep and inflammation markers are linked

You have been sleeping badly for weeks. Some nights you wake up several times, other nights you lie awake for ages, and in the morning you feel worn out. Then your results show a slightly raised CRP level, and you wonder: is one connected to the other?

Sleep and the immune system are closely linked. This article explains what studies really show about poor sleep and inflammation, why the link works in both directions, and what you can do to break out of the cycle.

Sleep and inflammation: what happens in the body

Inflammation is useful to begin with. When the immune system notices a germ or an injury, it sends out messengers. These messengers are called cytokines, for example interleukin-6, or IL-6 for short. The liver responds by producing C-reactive protein, or CRP. This is the inflammation marker most often measured in the lab.

During sleep, the nervous system, hormones and immune system tune in to one another. A review describes this connection as two-way: sleep supports the body's defences, and signals from immune cells in turn influence sleep (PubMed 31289370). If sleep is disrupted over a long period, the way the body regulates inflammation can also get out of step.

Lack of sleep and inflammation markers: what the studies show

In the sleep lab, researchers can watch what happens after too little sleep:

• One short night: Healthy adults stayed awake from 11pm to 3am. The next morning, certain immune cells called monocytes produced more IL-6 and TNF-alpha, two messengers that promote inflammation (PubMed 16983055).
• Three short nights: In a study from Uppsala, 16 young, healthy men slept for just over four hours a night for three nights. Afterwards, a pattern of proteins in their blood changed – a pattern that large population studies link to a higher cardiovascular risk, including messengers of the immune system (PubMed 40301994). Whether this leads to illness is something such a small, short study cannot show.
• Ten short nights: People who slept for just over four hours a night for ten nights ended up with higher CRP levels. In the comparison group with just over eight hours of sleep, the level stayed stable (PubMed 14975482).

And in everyday life? A large meta-analysis of 72 studies and more than 50,000 people found that people who report disturbed sleep have, on average, slightly higher CRP and IL-6 levels. Very long sleep was also linked to higher levels. Short-term, artificial sleep deprivation in the lab, on the other hand, showed no clear effect on these markers overall (PubMed 26140821).

To sum up honestly: persistently poor sleep is linked to slightly raised inflammation markers. On average the differences are small, and a few short nights do not add up to chronic inflammation.

The cycle in the other direction

The link does not only run from sleep to inflammation. During an infection the immune system makes you tired and sleepy, because signals from immune cells also reach the brain (PubMed 31289370). Pain works in a similar way: pain disturbs sleep, and poor sleep makes you more sensitive to pain. Long-term studies even show that sleep problems predict new or worsening chronic pain more reliably than the other way round (PubMed 24290442).

This is how a cycle can develop: pain or an inflammatory condition disturbs sleep, poor sleep increases sensitivity, and that makes the next night harder. It is not automatic, but it is a good reason to take sleep seriously.

Causes of poor sleep you might not think of

• Pauses in breathing (sleep apnoea): Loud snoring with pauses in breathing, morning headaches and severe daytime tiredness can be signs. Sleep apnoea is widespread and often goes unrecognised for a long time (PubMed 31300334).
• Stress and overthinking: If your stress system does not settle down in the evening, falling asleep is hard. Read more in the article Sleep problems caused by stress and inner restlessness.
• Waking up around 3am: Alcohol in the evening or the cortisol rhythm often play a part. Read more in Waking up at 3am every night.
• Pain, heartburn, needing to pee: Physical complaints interrupt sleep, often without you remembering it in the morning.
• Shift work and changing schedules: Your internal clock cannot keep up.

If you take sleeping pills or other medication that may affect your sleep, mention this to your doctor. Do not stop a prescribed medication without talking to your doctor first.

What you can do yourself

• Regular times: Get up at roughly the same time every day, including at weekends.
• Enough time in bed: Plan your sleep rather than treating it as whatever time is left over.
• Light in the morning, darkness in the evening: Daylight after getting up, dimmed lighting and little screen time before bed.
• Less alcohol in the evening: It mainly disturbs the second half of the night.
• Exercise during the day: A walk or some sport during the day, not right before bed.

For longer-lasting sleep problems, the European guideline recommends cognitive behavioural therapy for insomnia, or CBT-I, as the first choice (PubMed 28875581). In a study of older adults with insomnia, CRP also fell after this kind of therapy (PubMed 25748580). Ask your doctor about it.

Warning signs: when to see a doctor

• Your sleep problems last for weeks and seriously affect you during the day.
• You snore loudly with pauses in breathing or fall asleep during the day without meaning to.
• You have a fever, night sweats, unintended weight loss or swollen joints.
• A CRP result is clearly raised or stays raised on repeat tests.
• Your mood has been low for a long time.

A raised inflammation marker has many possible causes, from an infection to an inflammatory condition. Poor sleep can be one of them, but it is rarely the only one.

Measure instead of guessing: inflammation markers and sleep rhythm

• The OM Vital blood test includes high-sensitivity CRP (hs-CRP), along with ferritin, TSH, vitamin B12, vitamin D, folic acid, blood lipids and liver values.
• The Stress & sleep lab package combines a cortisol day profile with DHEA, melatonin in night-time saliva, neurotransmitter tryptophan metabolism and a cell stress profile in morning urine, as well as the Epigenetics Stress Monitor from capillary blood.

The results are building blocks for a conversation, not a diagnosis. The ORY team of experts or your doctor can help you interpret them.

In brief

• Sleep and the immune system influence each other.
• Even after one short night, certain immune cells produce more inflammatory messengers the next morning.
• Ongoing sleep problems are linked to slightly raised CRP and IL-6 levels; on average the differences are small.
• Inflammation and pain in turn disturb sleep. This is how a cycle can develop.
• Regular sleep times and, if needed, behavioural therapy for insomnia are the most important starting points.

Frequently asked questions

Can poor sleep cause inflammation?

Poor sleep can encourage inflammatory processes. People who report disturbed sleep have, on average, slightly higher CRP and IL-6 levels (PubMed 26140821). The differences are small, and other causes should always be considered too.

Does lack of sleep raise CRP levels?

In one lab study, CRP rose after ten nights of just over four hours of sleep (PubMed 14975482). When many studies were analysed together, however, short-term sleep deprivation in the lab showed no clear effect on CRP, whereas persistently disturbed sleep in everyday life did (PubMed 26140821).

How many nights of little sleep change inflammation markers?

After just one night of four hours' sleep, immune cells produced more inflammatory messengers the next morning (PubMed 16983055). After three short nights, the pattern of certain blood proteins changed in young men (PubMed 40301994). Whether this has long-term consequences remains unclear.

Can inflammation cause poor sleep?

Yes, the link works in both directions. Signals from immune cells influence sleep, for example during an infection (PubMed 31289370). Pain also disturbs sleep, and poor sleep in turn increases sensitivity to pain (PubMed 24290442).

Will inflammation markers go down again if I sleep better?

That cannot be predicted for everyone. In a study of older adults with insomnia, CRP fell after cognitive behavioural therapy for insomnia (PubMed 25748580). A repeat test after a few weeks shows how things look for you.

Which blood test shows inflammation?

CRP is the marker measured most often. The high-sensitivity version, hs-CRP, also picks up slight increases. A single result does not tell you where the inflammation comes from, though. That is something to discuss with your doctor.

Sources

1. Irwin MR. Sleep and inflammation: partners in sickness and in health. Nat Rev Immunol. 2019. PubMed 31289370
2. Irwin MR et al. Sleep deprivation and activation of morning levels of cellular and genomic markers of inflammation. Arch Intern Med. 2006. PubMed 16983055
3. Brandao LEM et al. The overlooked trio: sleep duration, sampling time and physical exercise alter levels of olink-assessed blood biomarkers of cardiovascular risk. Biomark Res. 2025. PubMed 40301994
4. Meier-Ewert HK et al. Effect of sleep loss on C-reactive protein, an inflammatory marker of cardiovascular risk. J Am Coll Cardiol. 2004. PubMed 14975482
5. Irwin MR et al. Sleep Disturbance, Sleep Duration, and Inflammation: A Systematic Review and Meta-Analysis of Cohort Studies and Experimental Sleep Deprivation. Biol Psychiatry. 2016. PubMed 26140821
6. Finan PH et al. The association of sleep and pain: an update and a path forward. J Pain. 2013. PubMed 24290442
7. Benjafield AV et al. Estimation of the global prevalence and burden of obstructive sleep apnoea. Lancet Respir Med. 2019. PubMed 31300334
8. Riemann D et al. European guideline for the diagnosis and treatment of insomnia. J Sleep Res. 2017. PubMed 28875581
9. Irwin MR et al. Cognitive behavioral therapy and tai chi reverse cellular and genomic markers of inflammation in late-life insomnia: a randomized controlled trial. Biol Psychiatry. 2015. PubMed 25748580