Do you ever wake up sweating during the night? If you’ve ever experienced a bout of nighttime sweating, you may have woken up shocked at how you could have unknowingly sweated so much. What’s more, your bed partner may also be shocked by this occurrence, as they might wake up covered in it! Nighttime sweat severity can range from a mild moisture to a full-blown “we need to get up and change the sheets.” So what causes nighttime sweating? Thermoregulation (temperature control during sleep) can be affected by many things, such as fluctuating blood sugar or blood pressure. It is also altered during different stages of sleep, with a lowering of body temperature as the body progresses through stages of sleep. Given this knowledge, might those who have apneas sweat more frequently?
To test this question, a research group set out to examine whether those with untreated sleep apnea sweat often more during the night. They also set out to test whether treating the sleep apnea would reverse these issues. A sweating frequency scale was administered to untreated sleep apnea patients. Sweatiness scores were calculated, and subjects were then analyzed based on whether they used continuous positive airway pressure (CPAP) or not. Sweatiness ratings were again assessed and compared with sweatiness scores from before treatment.
Results showed that of those who suffered from untreated sleep apnea, about 30% of the subjects reported nocturnal sweating at least 3 times per week. This is high relative to the 10% of non-apneic patients who report nocturnal sweating. Next, when comparing the CPAP users to the non-CPAP users, it was found that 33% of the non-CPAP users reported nocturnal sweating, and only 11% of the CPAP users were sweaty1.
This study suggests that those with untreated sleep apnea have a higher-than-normal frequency of nocturnal sweating. It also suggests that CPAP usage may actually abolish these symptoms, as those on CPAP seem to have sweating rates that are similar to the general, non-apneic population. Why does sleep apnea cause sweatiness? It may be that constant stress that is put on the body by apneas induces a physiological response that triggers sweating. Interestingly, in this sample, the younger population reported more sweating. Why is this so? Your guess is as good as mine. Overall, if you or someone you know suffers from night sweating, a sleep apnea screening should be performed and treatment should be sought!
1. Arnardottir, E. S., Janson, C., Bjornsdottir, E., Benediktsdottir, B., Juliusson, S., Kuna, S. T., ... & Gislason, T. (2013). Nocturnal sweating—a common symptom of obstructive sleep apnoea: the Icelandic sleep apnoea cohort. <em>BMJ open</em>, <em>3</em>(5).