Psoriasis is a chronic inflammatory condition causing the rapid buildup of skin cells, resulting in thick, scaly patches. For many people living with this disorder, symptoms—particularly intense itching (pruritus)—intensify at night, often disrupting sleep. This nocturnal worsening affects approximately 65 percent of patients with inflammatory skin disorders. It is driven by a complex interplay of internal biological timing, such as the body’s natural 24-hour clock, and changes in the skin’s barrier function.
How Circadian Rhythms Affect Inflammation
The human body operates on a roughly 24-hour cycle known as the circadian rhythm, which regulates numerous physiological processes, including the immune system and inflammation. This rhythm is a key factor in why psoriasis symptoms worsen at night. The body’s natural anti-inflammatory agent, the hormone cortisol, follows a predictable daily pattern.
Cortisol levels naturally peak in the early morning and gradually decline throughout the day. This creates a natural trough during the evening and sleep, effectively removing a significant brake on the inflammatory process. With less circulating cortisol to suppress the immune response, the body’s inflammatory pathways become more active.
Simultaneously, the activity of pro-inflammatory cytokines increases, reaching peak release during nighttime hours. These signaling proteins, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), are central to the pathogenesis of psoriasis. Heightened levels of these inflammatory mediators directly stimulate nerve endings in the skin, resulting in a more intense sensation of itchiness.
The circadian system is also linked to changes in skin blood flow, which has been shown to increase in the late afternoon and at night. This vasodilation accelerates the passage of inflammatory agents through the skin. This further contributes to the feeling of heat and itchiness in psoriatic plaques.
The Role of Skin Barrier Function and Sleep Environment
Beyond the body’s internal clock, the skin’s physical state and the sleep environment contribute significantly to the nighttime worsening of symptoms. Psoriatic skin has a compromised outer layer, resulting in a weakened barrier function. This damage means the skin is less effective at retaining moisture and protecting against external irritants.
The skin naturally loses moisture through Transepidermal Water Loss (TEWL), and this rate increases at night. For impaired psoriatic skin, heightened TEWL leads to excessive dryness in the plaques. The resulting irritation intensifies pruritus and makes the skin more vulnerable to external triggers.
Environmental Factors
The bedroom environment itself can also worsen symptoms. Elevated skin temperature, often caused by warm conditions or heat buildup from blankets, increases TEWL in psoriatic skin. This heat can also lead to sweating, which further irritates the plaques.
Physical factors, such as friction from bedding, stimulate the sensitive nerve endings in psoriatic skin. Moving against sheets and blankets causes irritation to the fragile plaques. Using abrasive fabrics can turn small movements during sleep into a source of constant irritation.
Strategies for Managing Nocturnal Psoriasis
Targeting nighttime worsening requires focusing on skin care and environmental control. To counteract increased water loss, apply a thick emollient or occlusive moisturizer immediately before bed. These products, such as petrolatum-based ointments or heavy creams, create a physical seal on the skin’s surface.
This occlusive layer limits Transepidermal Water Loss, effectively locking in moisture throughout the night to prevent dryness and itching. Wearing loose, soft cotton clothing or light bandages over treated areas is also helpful. This protective layer reduces friction from bedding and helps topical treatments remain in contact with the skin.
Environmental Adjustments
Adjusting the sleep environment mitigates heat and dryness. Keeping the bedroom cool lowers the skin’s surface temperature, which reduces inflammation and minimizes the rate of water loss. Using a humidifier adds moisture to the air, helping compensate for the skin’s diminished barrier function.
Medication Timing and Relaxation
For topical medications, timing the application to coincide with the drop in cortisol may maximize their anti-inflammatory effect. Applying prescribed steroid creams or other topical treatments before sleep is often the most effective approach. Relaxation techniques, such as deep breathing or meditation, can also help calm the nervous system, potentially reducing the stress-related component of the itch-scratch cycle.