Night Owl Waking Early in the Tropics

Patient: Hi. I’m a college student from New Jersey and I’m currently studying abroad in Costa Rica: this is my first time out of the Northeastern United States.I’m a night owl; at home, I normally stay up until 12pm-2am or later at times, and almost never wake up before 9am naturally. When I set an alarm for 7am or earlier, I wake up tired, grumpy, or fall asleep after turning it off, even if I slept for eight hours.This was my typical pattern in the months preceding my trip (summer vacation, sleeping in every day).However, in the three weeks I’ve been in Costa Rica, I consistently wake up at around 6:30 every morning, before my alarm clock even goes off, and I don’t even feel tired. In fact, I get tired earlier at night, 10pm-12pm, and I’m not even grumpy when I wake. Even when I do manage to stay up until 2am on a Friday or Saturday night, I STILL wake up at the same time.My question: why or how has my sleep-wake cycle changed so drastically and instantaneously?Is it related to Circadian rhythm, and being in a tropical location? Many other study abroad students here from the US say they have experienced this phenomenon as well, and attribute it to getting more sunlight here. However, we are in the middle of the rainy season, and it pours for at least a few hours every day!Thanks for reading. I know this isn’t actually a sleeping ‘problem’ but we are all wondering what’s going on with our bodies and brains.Pura vida!