An itchy vulva, medically termed pruritus vulvae, is a common experience that ranges from a mild annoyance to an intense, disruptive sensation. While many conditions cause this irritation, the specific intensification of the itch at night is a distinct phenomenon. Understanding why this nocturnal worsening occurs requires looking at both the initial triggers and the physiological changes that happen as the body prepares for sleep.
Common Causes Related to Infection
The most frequent causes of vaginal or vulvar itching are imbalances in the natural microenvironment, leading to infection and inflammation. Candidiasis, commonly known as a yeast infection, is a fungal overgrowth that affects up to 75% of women. This overgrowth is characterized by intense itching, burning, and a thick, white, “cottage cheese-like” discharge.
Another common cause is Bacterial Vaginosis (BV), which results from an imbalance where beneficial Lactobacilli bacteria are replaced by an overgrowth of other organisms. While BV is known for a thin, grayish-white discharge and a distinct fishy odor, it can also cause significant vulvar irritation and itching. Certain sexually transmitted infections (STIs), such as Trichomoniasis, are also potential sources of inflammation. These infections irritate the sensitive tissues, generating the initial sensation of itchiness.
Environmental and Irritant Triggers
Beyond infections, the sensitive skin of the vulva can react strongly to external chemical and physical irritants, leading to contact dermatitis. Allergic or irritant reactions are triggered by a wide range of common household and personal care products. These include scented soaps, bubble baths, feminine hygiene sprays, and the dyes or perfumes found in laundry detergents and fabric softeners.
Friction and moisture retention also contribute to irritation. Wearing tight-fitting clothing or synthetic underwear can trap heat and sweat, creating a warm, damp environment ideal for skin irritation and the proliferation of microbes. Hormonal shifts, particularly the drop in estrogen during perimenopause and menopause, can cause the vulvar skin to become thinner and drier. This condition, called genitourinary syndrome of menopause, compromises the skin’s barrier function, making it susceptible to chronic itching and inflammation.
Why Itching Becomes Worse at Night
The intensification of itching at night, known as nocturnal pruritus, is due to specific physiological and behavioral changes that occur during rest. One primary reason is the reduction of daytime distractions, which allows the brain to become hyper-aware of sensations. This makes a low-level itch feel significantly more intense. The body’s internal circadian rhythm also plays a direct role in regulating inflammatory processes.
Levels of certain inflammatory mediators, such as histamine, often follow a circadian rhythm and may increase in the evening hours, contributing to the sensation of itch. Conversely, the body’s natural anti-inflammatory hormone, cortisol, reaches its lowest concentration during the night. This leads to a decreased ability to suppress inflammatory reactions. Thermoregulation changes also compound the issue, as the skin releases heat to lower the core body temperature for sleep. This increase in skin temperature and blood flow enhances the inflammatory response and the perception of itchiness.
Next Steps Seeking Medical Attention
Relieving nocturnal itching begins with simple changes, such as switching to 100% cotton underwear and avoiding all scented products. Applying a clean, cool compress to the vulva can provide temporary relief from acute inflammation and discomfort.
Persistent itching that lasts more than a few days, or is accompanied by other symptoms, requires professional medical evaluation.
When to See a Doctor
Red flag symptoms that warrant a visit to a healthcare provider include:
- Abnormal discharge
- A foul odor
- Pain during urination or intercourse
- Visible sores or blisters
Because many different conditions—from infections to skin disorders—can cause pruritus vulvae, self-treating without a diagnosis risks worsening the underlying cause. A medical professional can perform necessary tests, such as a vaginal swab or biopsy, to determine the exact cause and prescribe targeted treatment like antifungal medications or topical steroids.