Acclimatization is the process of getting used to a new environment or different conditions. When your body acclimatizes, it gradually adjusts so you can function normally in surroundings that felt uncomfortable at first.

The most dramatic example happens with altitude. When mountain climbers attempt peaks like Mount Everest, they spend weeks at base camps letting their bodies acclimatize to the thin air. Their bodies produce more red blood cells to carry oxygen more efficiently. Without this adjustment period, the lack of oxygen at high elevations could make them sick or worse.

But acclimatization happens in everyday situations too. When you jump into a cold pool, the water feels shockingly chilly at first. After a few minutes, your body acclimatizes and the temperature feels normal. Students who move to a new country acclimatize to different weather, food, and customs. Even switching from summer vacation back to school requires acclimatization: waking up early feels brutal the first few days, but your body soon adjusts to the new schedule.

The key idea is that acclimatization takes time. Your body or mind can't instantly adapt to major changes. It needs a period of adjustment, like warming up before exercise or adjusting your eyes when walking from bright sunshine into a dark room.