MCAS & Difficulty Sleeping at Night: Why Mast Cells Can Disrupt Your Rest
Struggling to fall asleep—or stay asleep—may be more than just insomnia. For people living with mast cell activation syndrome (MCAS), nighttime can be one of the most challenging parts of the day.
While MCAS is known for causing a wide range of unpredictable symptoms, its impact on sleep quality is often overlooked. In reality, mast cell activity plays a major role in sleep disruption—and understanding this connection can help you find relief.
Why MCAS Can Make It Hard to Sleep
Mast cells release chemicals like histamine, prostaglandins, and cytokines that trigger inflammation and a wide variety of symptoms. These chemicals impact neurological and physiological processes that are essential for deep, restful sleep.
For those with MCAS, mast cells can become overactive at night, leading to symptoms that make it difficult to fall asleep, stay asleep, or feel refreshed in the morning.
Common Nighttime Symptoms of MCAS
MCAS-related sleep issues can look different for each person, but some of the most commonly reported nighttime symptoms include:
Sudden awakenings or restlessness
Feeling too hot or too cold
Joint, bone, or muscle pain
Itchy skin or tingling sensations
Heart palpitations
Abdominal cramps, bloating, or constipation
Dry cough or throat tightness
Night sweats or chills
Headache or migraine
Nasal congestion
Nausea or queasiness
Feeling “on edge” or anxious
Restless legs syndrome
These symptoms often fluctuate, making it even harder to establish consistent, restorative sleep patterns.
The Histamine Connection: Why Nighttime Is Worse
One of the key reasons MCAS symptoms can flare up at night is due to the body’s natural histamine cycle.
Histamine levels tend to rise in the evening and peak overnight, especially during the early morning hours. In individuals with MCAS, where mast cells are already unstable, this natural surge of histamine can trigger a cascade of symptoms—just as you're trying to rest.
Histamine is also a wake-promoting neurotransmitter, meaning it can make you feel wired, alert, or overstimulated—exactly the opposite of what you need for sleep.
Tips for Managing MCAS Sleep Disruption
While improving sleep with MCAS takes time, the following strategies may help reduce symptom severity and promote more restful nights:
Support histamine clearance
This can involve consulting with an MCAS-aware healthcare provider about low-histamine diets or DAO enzyme support, and avoiding high-histamine foods in the evening, such as leftovers, aged cheese, or alcohol
Calm the nervous system
This can be done through use of gentle techniques like deep breathing, meditation, guided imagery, and considering somatic therapy, vagus nerve stimulation, or grounding exercises.
Optimize sleep hygiene
Keeping your bedroom cool and dark, establishing a consistent bedtime routine, or limit screen time before bed can be helpful.
Consider nighttime medication timing
It can be beneficial to work with an MCAS-aware healthcare provider to time antihistamines or mast cell stabilizers in a way that supports nighttime symptom control.
Tracking your symptoms in a sleep and symptom journal
This can help you identify triggers or patterns that worsen your sleep.
If you’re dealing with sleepless nights due to MCAS, know that you’re not imagining it—and you’re certainly not alone. Poor sleep isn’t just exhausting; it can worsen mast cell activation, create a feedback loop, and affect your ability to heal.
Understanding the link between mast cells, histamine, and sleep disruption is a powerful step toward building a plan that works for your body. With the right support and strategies, more restful nights are possible.
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DOI: 10.1038/srep39934; PMID: 31994488; PMID: 32595651; PMID: 30034393; PMID: 35853794; PMID: 30794367; PMID: 32328892; PMID: 38003876
Disclaimer: This blog post is for informational purposes only and shall not be construed as behavioral health or medical advice. It is not intended or implied to supplement or replace treatment, advice, and/or diagnosis from your own qualified healthcare provider.