Night sweats and hot flashes with or without drenching sweats are very common in CF. At some time nearly all CFers experience them. It can be chronic or episodic. Chronic sweats may wax and wane, but it's always an issue. There's a CF issue causing this, but I'm getting ahead of myself. Episodes of sweats have a less direct trigger like certain infections. For example, the mini series, "Downton Abbey", in the pre-antibiotic days, one of the daughters is brought back from the brink of death with a large injection of adrenaline, epinephrine, the ultimate stimulant of the immune system. CFers are generally taxed out on stress hormones. The result of stress hormones surging throughout the body can cause sweats.
The cause is simple, we have CF. The exact trigger most likely changes depending on what is the current severity of the many battles going on in our bodies. Infections are being fought all over the body of a CFer. Unofficial statistics indicate that for most of the life of a CFer, an illness knocks us down fast and the recovery is equally fast, most times. We are often thin and though we're not great at digestion and absorption of nutrients, the fact remains that we need far more calories than a person not fighting infection, inefficiencies in the transportation of everything from hormones to water and oxygen. Most of us are hypermetabolic despite tests that say we're not. I have two friends who are too thin, that I do amateur (unlicensed) physical therapy and massage. One has CF and the other is the victim of PEM or Protein Energy Malnutrition. It becomes obvious that I am a heater, as are my grateful charges. The amount of body heat emanating from two thin people is astonishing. I've got to believe that I am in good company, most parents and young adults are aware of this phenomenon. Add the fact that the normal cooling system people use, sweating, doesn't work when we need it to.
We live in a kind of cold war with stockpiles of antibodies, antigens and fighter cells, far exceeding the amounts a healthy non CFer would possess. The sheer volume of bacterial infections in a CFers lungs, head, and the endocrine system is astonishing. Our gut, mostly the GI tract keeps our immunity on Red Alert by routinely introducing the body to novel infections for the body to design antibodies or eliminate the test infections via fighter cells like lymphocytes and lukocytes. This is a natural function of the gut and it occurs in everybody, CF or not. It helps us understand why it's called the center of our immune system.
Whether it's a lung infection or a battle of thick mucus trying to transport hormones in the thyroid gland or the adrenal glands and kidneys, these are triggers that result in sweats. I believe that the connection with the autonomic (sympathetic/parasympathetic) nervous system is a major factor behind this. CF is deeply connected to the autonomic or Vagus nerve system. Think about it. Lung pain, minus the bronchials, doesn't hurt directly. The pain may refer to the back, sometimes the ribs, but not the lungs. Pancreatitis and Cholestasis might be painful where the organs are, but most often the gallbladder feels like an epic case of heartburn, or a burp/belch caught up high in the stomach. I had one that sent me to the ED because of the similarity to a heart attack. Both the gallbladder and pancreas refer pain to the back, around or between the shoulder blades. Both feel like heartburn, called epigastric pain. The sinuses and the GI tract show pain more directly, and infection can easily translate to night sweats.
All of this is common sense and sometimes it just doesn't feel like the cause. I researched this about a year ago because of people suffering from sweating calves, ankles and feet, or forearms and hands. Do all CFers have sweaty clammy palms and soles? I am really interested, seriously. Back in 2012 I had some event that ended in the ED. My personal guess was a thyroid storm but they didn't run a thyroid assay so I will never know. The sweating of my hands and feet was a medical mystery. I held my hand above a measuring cup and within two minutes, I had sweat a quarter cup of super salty water. My shoes were ruined as they filled and overflowed with the same salty solution.
It turns out that our thyroid gland does more than wrap around the lower pharanx/larynx. The thyroid gland hangs like a beard, entwined around the wind pipe, it transitions from interconnected thyroid nodules to lymph nodes. Lymph nodes fill a large amount of the chest, clustered around the heart and lungs.
The odd population of thyroid nodules and lymph nodes in an area generally under attack by allergens, and infection and the results can be a bizarre response of calf-to-sole and arm-to-palm sweats, often at night. This is for real and not funny in the least. I haven't been able to find research connecting this phenomenon to night sweats, but by being mostly a night sweat of the outer limbs, I believe they are related. This isn't a phenomenon for CF alone. Most people who have this condition are dealing with a chronic illness as well, so immunity and the autonomic system are likely the root.
Look into cool pillows and my favorite, a tent frame for the feet. Anyone who has had foot surgery or any reason to keep the covers off the feet has seen them. Medical appliance stores sell the frames. Good hydration, including balanced electrolytes can't hurt.
Hope this helps,