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.
Hot flashes can be accompanied by other uncomfortable sensations, such as heart palpitations, a pressure feeling in the head, or feelings of dizziness, faintness or weakness. When hot flashes occur during the night, they can cause sleeplessness (insomnia), resulting in poor concentration, memory problems, irritability and exhaustion during the day.