His chronicle of his trip, The naturalist on the River Amazons, became a bestseller when it was published in 1863.
Hot flashes and nausea are most commonly caused by hormonal imbalances in the body, most notably, by sex hormones. For women, a decrease in estrogen is often to blame, whereas in men, testosterone deficiency can create the problem. Sometimes, the symptoms occur for reasons not related to those hormones at all.
When it is hot outside, or a room is overheated, these symptoms can become exaggerated. They can also lead to night sweats and insomnia. Other Causes for Hot Flashes. When someone experiences hot flashes, a doctor can tell with a simple blood test if the problem is related to menopause or due to some other reason. 1  Menopause usually occurs in the 50s, so when someone much younger has hot flashes, physicians will often look for additional causes. Some of the most common ones include: 1  Thyroid problems, such as hyperthyroidism, which causes an overabundance of thyroid hormone, can increase the bodyâs metabolism and lead to hot flashes and sweating. 2  Food and drink, including spicy foods, caffeine, and alcohol, can trigger hot flashes.