Modern homes are often poorly designed for cooling, leading many to rely on air conditioners during the summer. However, following a few simple strategies can significantly reduce the need for these energy-heavy devices, especially in regions with moderate climates. Understanding how the body cools itself naturally can lead to more effective and sustainable sleep practices. During sleep, body temperature typically decreases, and high nighttime temperatures can disrupt this process, resulting in poor sleep quality, fatigue, and even dehydration over consecutive nights. The most effective cooling strategy begins during the day, a step often overlooked but crucial for maintaining a comfortable indoor temperature at night. This relies on the principle of thermal inertia, which involves preserving the coolness accumulated during the night and preventing heat from entering the home. Between noon and 4 p.m., when temperatures peak, it’s important to close windows, shutters, and curtains to block solar radiation and limit internal heat sources. In the evening, when outside temperatures drop, opening windows on opposite sides of the house can create air currents that naturally cool the interior. Keeping the room dark also helps prevent insects and maintains a cooler environment. Several simple techniques can further enhance cooling without the need for air conditioning. For example, applying a slightly damp and cool towel to the neck, wrists, or ankles can promote heat dissipation, as these areas have blood vessels close to the skin. A foot bath in cold water for ten minutes can also help lower body temperature, making it easier to fall asleep. A cooled pillowcase placed in the freezer before bedtime can provide immediate comfort. However, very cold showers or drinks are not effective, as they can cause blood vessels to contract, limiting heat loss. Instead, a lukewarm shower allows for gradual cooling, while letting the skin dry naturally enhances the effect through evaporation. While these methods can be highly effective, they are best suited for dry climates. In humid environments, the evaporation of sweat, which is essential for cooling, becomes less efficient. This means that these techniques may be counterproductive during hot and humid weather. Additionally, using fans can improve comfort by accelerating sweat evaporation, but they do not lower air temperature. Their effectiveness diminishes above about 35 degrees Celsius and can even contribute to dehydration. While these cooling strategies are aimed at improving comfort, it’s important to remember that extreme heat can be life-threatening. High temperatures pose significant risks to vulnerable groups such as the elderly, infants, pregnant women, and those with chronic illnesses. Heatwaves have been responsible for thousands of deaths, including over 70,000 in Europe in 2003. Recognizing the signs of heat-related illness—such as headaches, nausea, confusion, or a cessation of sweating—is crucial. If someone experiences a high body temperature along with behavioral changes, it is essential to seek immediate medical help, as heatstroke can be fatal.