Why Does Inflammation Increase Overnight?

September 28, 2025 •

3 min read

Did you know that many inflammatory conditions, such as arthritis, often have symptoms that worsen during the night? This phenomenon, where inflammation increases overnight, is linked to a complex interplay of hormonal shifts and your body’s natural rhythms.

Quick Summary

Your body's natural 24-hour clock, or circadian rhythm, causes hormonal shifts like a nightly drop in cortisol, reducing anti-inflammatory effects and allowing inflammation to temporarily increase while you rest.

Key Points

Circadian Rhythm: The body's internal clock causes hormone changes that increase inflammatory activity at night.
Cortisol Drop: Lower levels of anti-inflammatory cortisol at night reduce the body's ability to control inflammation.
Increased Awareness: Fewer distractions at night mean the brain focuses more on pain signals.
Reduced Movement: Staying still allows inflammatory fluids to gather in joints, increasing stiffness.
Sleep Deprivation: Poor sleep disrupts immune function, creating a cycle that can worsen inflammation.
Dietary Impact: Eating inflammatory foods or heavy meals before bed can intensify the natural nightly inflammatory response.

The Circadian Rhythm and Your Immune System

Your body's internal 24-hour clock, the circadian rhythm, controls more than just sleep; it also governs immune function. This internal clock balances pro-inflammatory and anti-inflammatory signals daily. Immune activity is generally lower when you're active during the day. As evening comes, this balance shifts, and the immune system becomes more active. This increased activity helps fight infections and heal, but can make inflammatory symptoms worse at night.

Hormonal Fluctuations: The Cortisol Connection

Changes in hormones are a key reason for nighttime inflammation, particularly the fluctuations of cortisol. Cortisol, a natural steroid hormone, acts as a strong anti-inflammatory agent.

Cortisol levels are typically highest in the morning and decrease at night. This decline in anti-inflammatory cortisol at night can allow inflammation to increase, potentially worsening symptoms. Other hormones like melatonin, estrogen, and testosterone also play a role and fluctuate throughout the day and night.

The Role of Stillness and Gravity

Movement during the day helps circulate fluids and reduces stiffness. Spending extended periods in stillness at night can allow inflammatory fluids to accumulate in joints and tissues, contributing to increased swelling, stiffness, and discomfort, especially in conditions like arthritis.

Pain Perception and Psychological Factors

Daytime activities often distract from pain. At night, with fewer distractions, the brain may focus more intensely on internal pain signals. Stress and anxiety can also exacerbate pain perception and contribute to a cycle of discomfort and poor sleep.

The Vicious Cycle of Sleep and Inflammation

There is a two-way relationship between poor sleep and inflammation; inflammation can disrupt sleep, and lack of sleep can increase inflammation. Just one night of insufficient sleep can activate inflammatory pathways. Poor sleep can also increase pro-inflammatory cytokines, potentially increasing pain sensitivity and contributing to chronic inflammation.

Lifestyle Factors and Their Nighttime Influence

Certain daily habits can worsen nighttime inflammation. Eating large or inflammatory meals late in the evening may trigger inflammation during sleep. Consuming alcohol or caffeine late in the day can disrupt sleep, impacting the sleep-inflammation cycle. Chronic stress can also interfere with the normal timing of cortisol release.

Comparison of Daytime vs. Nighttime Inflammation Factors


Factor	Daytime Condition	Nighttime Condition
Hormonal Balance	High cortisol suppresses inflammation	Low cortisol allows inflammation to rise
Physical Activity	Movement helps circulate fluids and reduces stiffness	Stillness allows inflammatory fluids to pool
Pain Perception	High distractions mask pain signals	Low distractions increase awareness of pain
Immune Response	General immune activity is dampened	Immune response is heightened and more active
Sleep Quality	Restorative sleep supports immune function	Poor sleep intensifies inflammatory signaling

Strategies for Managing Nighttime Inflammation

Key strategies include optimizing sleep hygiene with a consistent schedule, incorporating gentle movement during the day and evening, using strategic therapies like warm or cool compresses on affected areas, and using pillows for supportive positioning of painful joints. Dietary adjustments like avoiding large or inflammatory meals late can help. Discussing supplements like magnesium with a doctor may also be beneficial.

Conclusion: Taking Control of Your Nighttime Discomfort

Increased inflammation overnight is a common phenomenon linked to the body's natural circadian rhythms and hormonal changes. Understanding these factors is crucial for managing symptoms. Lifestyle adjustments focusing on sleep, diet, stress management, and gentle therapies can help alleviate nighttime discomfort. For further reading on the biological clock's influence on inflammation, you can explore research on the circadian regulation of inflammation.

Frequently Asked Questions

Yes, for many people, especially those with chronic conditions like arthritis, it is a common and biologically predictable pattern driven by hormonal and circadian changes.

Cortisol, a natural anti-inflammatory hormone, naturally decreases at night. This drop reduces the body's ability to suppress inflammation, which can allow it to temporarily increase.

Yes, inadequate or disrupted sleep can interfere with immune regulation and lead to higher levels of pro-inflammatory markers, which can make inflammation worse.

Prolonged stillness during sleep allows inflammatory chemicals and fluids to accumulate in joints and tissues, which can lead to increased stiffness and pain.

Strategies include using heat or cold therapy, gentle stretching before bed, avoiding inflammatory foods late at night, and practicing good sleep hygiene.

While often linked to common chronic issues, persistent or severe nighttime inflammation should be evaluated by a healthcare provider to rule out or properly manage underlying conditions.

Yes, eating large meals or inflammatory foods close to bedtime can put stress on your body's systems and worsen the inflammatory responses that occur naturally during sleep.

Yes, chronic stress can disrupt the normal circadian rhythm of cortisol, and anxiety can heighten your perception of pain signals, both of which can worsen nighttime inflammation.