I wake up in the middle of the night and can’t get back to sleep

Waking up in the middle of the night at a specific time and always that time has a lot to do with the acupuncture meridian system 24-hour clock. For example, 3am to 5am is the time for the lung meridian to be more active. Constantly waking up during that time could very well be due to something irritating the lungs such as poor air quality, lung congestion, smoking, etc. Waking up at different times and sometimes being able to fall back asleep and sometimes not, is more of an adrenal gland issue. Cortisol levels should normally be low at night and then rise in the morning around 6-7am. Spikes in cortisol levels during sleep from unresolved stress can trigger this sleep problem. Additionally, the pineal gland which secretes melatonin, turns on at night while all the other hormones turn themselves down. An under active pineal gland can result in sleep problems. Pineal gland dysfunctions are also something to consider with any jet lag issues.