It’s a common scene: the room is warm, the fan is on full blast, and yet, you still pull at least a thin blanket over yourself before drifting off to sleep. Even on the hottest nights, many people feel strangely uncomfortable trying to sleep without something covering them. But why is that? The answer lies in a mix of biology, psychology, and habit.

First, our body follows a natural sleep cycle controlled by something called the circadian rhythm. As bedtime approaches, our body temperature begins to drop slightly, signaling that it’s time to rest. Using a blanket helps maintain that temperature drop in a comfortable way, preventing sudden chills or fluctuations that could disturb sleep. Even if it feels warm outside, our body still expects this temperature regulation process, and a blanket supports it.

There’s also the role of melatonin, the hormone that helps us fall asleep. Melatonin production increases when our body cools down at night. Blankets create a stable environment that allows this process to work effectively. Without a covering, our body may sense instability in temperature, which can interfere with the melatonin release and make it harder to feel truly relaxed.

Beyond biology, there’s a strong psychological comfort associated with being covered. From childhood, many of us associate blankets with safety and security. Being tucked in often signaled protection and care. Even as adults, a blanket provides a subtle sense of being “shielded,” helping us feel calmer before sleep. This sense of security reduces anxiety and makes it easier for the brain to transition into a state of rest.

Additionally, blankets provide a form of deep pressure stimulation, a calming effect similar to a gentle hug. Studies have shown that this kind of pressure can lower stress levels, reduce heart rate, and promote feelings of relaxation. That’s why even a light sheet can make a big difference when trying to fall asleep.

Of course, no one wants to feel overheated during the night, which is why many people opt for lighter materials in the summer, such as cotton or bamboo sheets. These thinner blankets offer the same psychological comfort without trapping as much heat. So while we may adjust the thickness of our blanket based on the weather, the need for some kind of covering often remains.