Inclusion Criteria:  Have received a diagnosis of prostate cancer and have received treatment with GnRH agonist or antagonist therapy or orchiectomy at least 1 month prior to enrollment. May have received prior definitive radiation therapy or surgery (>60 days prior to study). Have bothersome hot flashes (occurrence ≥ 28 times per week and at least moderately bothersome). Presence of hot flashes for >30 days prior to study entry. Have a working smartphone (iPhone 6 or greater; or Android 8.0 or greater). Willing to downloading and use the Embr thermal device companion app on their phone Willing to wear the Embr thermal device for 4 weeks, and charge and sync the device daily In order to complete the mandatory patient-completed measures, participants must be able to speak and/or read English  Exclusion Criteria:  Planned treatment with chemotherapy and/or any medical intervention that will impact hot flashes, sleep, or other daily activities of daily life during the 4-week study. History of a known sleep disorder, other than insomnia (eg, obstructive sleep apnea, restless leg syndrome), or medical or psychiatric condition that affects sleep, or undergoing treatment for insomnia. History of cognitive impairment or dysfunction. Seizure history, history of recurrent falls, or known brain metastases. Uncontrolled intercurrent illness. Individuals with a second malignancy other than non-melanoma skin cancers. Individuals taking psychotropic medications or illicit drugs that may alter cognition, concentration, or behavior. Individuals taking prescription sleep medications. Individuals who report consuming more than 7 alcoholic beverages/week and/or frequent alcohol consumption within 2 hours prior to bed.