Eczema, also known as atopic dermatitis, is a chronic inflammatory skin condition that causes dry, intensely itchy, and inflamed patches on the skin. This persistent itch (pruritus) is the most common symptom for sufferers. The problem often worsens at night, a phenomenon known as nocturnal pruritus, which severely disrupts sleep. This nighttime intensification is driven by a complex interplay of the body’s internal clock, environmental factors, and behavioral patterns.
The Biological Clock and Immune Response
The human body operates on a natural 24-hour cycle called the circadian rhythm, which regulates functions like the immune system and hormone release. This internal clock is a primary reason why eczema itch tends to peak in the late evening and during the night. The body’s natural anti-inflammatory defense drops significantly as the day ends.
This reduction is due to the natural dip in the hormone cortisol, a powerful anti-inflammatory agent that peaks in the morning and reaches its lowest levels around midnight. With less cortisol circulating, the inflammatory response is less suppressed, allowing inflammation in the skin to increase. Simultaneously, the production of immune signaling proteins called cytokines, which drive inflammation and itch, tends to peak during the night.
Another physiological change that contributes to nocturnal itching is the subtle shift in body temperature. Although the core body temperature decreases slightly to facilitate sleep, the skin temperature rises as the body dilates blood vessels to shed heat. This increased blood flow warms the skin, stimulating nerve endings and heightening the perception of itch. This combination of reduced anti-inflammatory hormones, increased inflammatory signals, and warmer skin creates a perfect storm for intense nocturnal pruritus.
Environmental Factors and Skin Barrier Function
The physical state of the skin barrier and the bedroom environment introduce external factors that compound nighttime itch. Eczema skin has a compromised outer layer (stratum corneum) that struggles to retain moisture. This vulnerability is exacerbated during sleep due to transepidermal water loss (TEWL).
The skin naturally loses more moisture at night, and this water loss is greater in eczema-affected skin, leading to dehydration and dryness. When the skin becomes drier, nerve endings are more easily irritated, intensifying the sensation of itch. This effect is worsened in bedrooms with low humidity, common with indoor heating during colder months.
Physical irritants in the sleep environment also contribute to the heightened itch response. Coarse or synthetic bedding materials can cause friction against sensitive skin, leading to mechanical irritation. Overheating from heavy blankets or a warm room can trigger sweating, and the salt in sweat can sting and irritate the skin, weakening the barrier.
The Feedback Loop of Sleep and Scratching
While biological and environmental factors initiate the itch, the shift in mental focus at night drives the problem. During the day, the brain is occupied by work and other stimuli, which distracts from the sensation of itching. Once a person is settled in bed with no external distractions, the brain shifts its attention inward, increasing the perception of internal sensations, including the itch.
Scratching often occurs unconsciously during lighter stages of sleep or brief awakenings (micro-arousals). This subconscious scratching damages the skin barrier, leading to more inflammation and the release of itch-inducing chemicals. This creates a vicious cycle: itch causes scratching, which damages the skin, leading to inflammation and a worse itch the following night.
The chronic sleep disruption caused by this cycle introduces another layer of complication. Poor sleep quality prevents the body and the skin from completing their natural repair processes. Lack of restorative sleep can increase stress and fatigue, which are known to trigger or worsen eczema flares.
Practical Steps for Managing Nocturnal Itch
Managing nighttime itching requires addressing physiological, environmental, and behavioral factors. One effective strategy is adopting a consistent “soak and seal” routine shortly before bed. This involves a short, lukewarm bath followed immediately by applying a generous layer of prescribed topical medication or a thick, fragrance-free emollient to trap water in the skin.
Controlling the environment is another practical step to mitigate external triggers. Aim to keep the bedroom cool, ideally between 60°F and 67°F (15–19°C), to prevent overheating and vasodilation. Using a humidifier can counteract the increased transepidermal water loss caused by dry air, helping to maintain skin hydration throughout the night.
To address the scratching feedback loop, use soft cotton gloves or scratch mitts to protect the skin from damage during unconscious scratching. Trimming and filing fingernails short and smooth minimizes trauma if scratching occurs. Incorporating relaxation techniques, such as deep breathing or gentle stretching, into the bedtime ritual can help calm the nervous system and reduce the mental focus on the itch sensation.