19°C is above the ideal 16–18°C range, but not dramatically. Most people will still fall asleep — it's staying asleep through the early hours that becomes harder, because your body can't complete its natural cooling cycle.

The dew point — 18°C — is the real problem tonight. High dew point means your sweat can't evaporate, which is your body's primary cooling mechanism. This is why humid heat feels worse than dry heat at the same temperature, and why a fan helps more than you'd expect.

The air barely cools overnight — just -0.5°C between bedtime and 4am. Your body's circadian rhythm expects a temperature dip during the night. When the environment doesn't provide one, sleep becomes lighter and more fragmented, even if you don't fully wake.