Temperature is a strong regulator of sleep. If your core body temperature isn't allowed to drop or only drops minimally, you will have great difficulty sleeping.
One solution when it is hot and you have no way of cooling the area is to place your hands and feet in cold water. This will draw some of the core body heat out. As well, a cool washcloth on head and neck can do something similar. If you have a fan (and ice) you can pace the ice in a bowl in front of the fan and it will blow cool air toward you.
The idea is to drop your core body temp enough to signal your brain to fall asleep. You may awaken again when the temp rises, and the idea would be to repeat the action-not ideal but at least a method to achieve some sleep.
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