Things That Go Itch in the Night
By Dr. Paul Ehrlich
Why do allergies light up when sun goes down?
On a recent Doctor Radio program, a caller asked why her child’s eczema seemed so much worse at night than when she woke up in the morning. I told this mother that the secretion of cortisol, the precursor of cortisone, our own natural anti-inflammatory hormone, is at its highest point in the morning and lowest at night. Parents tell me that they go to wake up their children in the morning and find them lying asleep still scratching, before their adrenal cortex starts to kick into gear. The perennial recommendations that children be wrapped in wet pajamas, rubbed with topical steroids and have their nails trimmed can help compensate for the down cycle. Parents also tell me that their kids’ itching improves dramatically when they are distracted from their health issues by active play, but since playtime is associated with daytime, there may be more to it than just taking their minds off the eczema.
Hormones play a role not only in suppressing atopic dermatitis but also in the very fact of being awake and active. For example, adrenalin, which is the body’s own epinephrine, follows the same circadian rhythm. This may account for the reports I hear about evening doses of food allergens for oral immunotherapy, an experimental therapy not approved for private practice, producing more severe responses than morning doses. The body’s defenses are weaker at the later hours.
Another naturally occurring substance that operates according the clock is histamine, which is familiar to anyone who has ever sneezed during pollen season. It is released by mast cells and basophils when they encounter an allergen. But histamine has another function. It is a neurotransmitter that plays a vital role in governing our cycles of sleeping and waking. Like cortisone and adrenalin, brain histamine is lowest at night and highest in the morning. As we explain in our book, the first-generation Benadryl can pass through the brain-blood barrier with ease, neutralizing not only the histamine released during an allergic reaction but the histamine that is keeping us awake as well, which is why we are warned not to drive or operate heavy machinery. Newer antihistamines do this to a lesser extent, although some of us are still very sensitive. (When Zyrtec—cetirizine–was brand new and available by prescription only, a rep from the company that made it gave me one in the morning to show how non-sedating it was, and my staff had to cancel all my patients for the day.)
Even for non-allergic people, managing the cycles of these substances is an important part of health. Our circadian rhythms are attuned to the days when there were no electric lights, TVs, iPads, and other things that occupy many of us long into the night. As far as your adrenal cortex is concerned, we’re still living in caves, dozing as the fire dwindles, and hoping that its fading light will keep saber-tooth tigers away. But if either a tiger or an allergen does attack, we will be jolted by the release of adrenalin and possibly other chemicals that will make it hard to go back to sleep, which will, in turn, make us sleepy the next day. The combination of airway allergies and overweight can make matters worse, as Larry has written, because the body’s defense against breathing stoppages during sleep—aka sleep apnea—is a spontaneous jolt of adrenalin.
We should all be managing our days and nights with respect to that inner cave man, not just allergy sufferers, but those with allergies have to show these powerful chemicals an extra measure of respect. Control inflammation, avoid your triggers, use dust-mite resistant bedding, control weight, keep skin hydrated. AND turn off the TV and computer an hour before bedtime.