Why Do We Feel Sleepy When It Rains?

Many people have experienced an unusual drowsiness on rainy, overcast days—even after a full night’s sleep. This phenomenon is not unusual and can be explained by various physiological and psychological responses to changes in weather conditions.

1. Reduced Light Increases Melatonin Production

Rainy days are often cloudy, reducing the amount of natural light. Light is a key regulator of the human biological clock, particularly in controlling the production of melatonin, a hormone that influences the sleep-wake cycle.
When light levels decrease, the brain's pineal gland interprets it as evening or nighttime and produces more melatonin, leading to feelings of drowsiness and relaxation.

2. Lower Atmospheric Pressure and Reduced Oxygen Levels

Before it rains, atmospheric pressure often drops, which can result in thinner air and reduced oxygen availability. This may lead to decrease oxygen circulation in the bloodstream and to the brain, causing fatigue and increase sleepiness.

3. The Relaxing Effect of Rain Sounds and Atmosphere

The sound of rain typically resembles white noise, a steady, continuous sound that helps reduce stress and induces relaxation. Research shows that rain sounds can stimulate the parasympathetic nervous system, which promotes rest and sleep.

4. Cooler Temperatures Encourage Rest

Rain often brings cooler temperatures, which can trigger the release of neurotransmitters such as serotonin, known for its calming effects. A drop in temperature also creates a more sleep-conducive environment, making it easier for the body to relax and wind down.

Feeling drowsy when it rains is a natural reaction influenced by multiple factors—reduced light leading to increased melatonin, lower pressure and oxygen levels, soothing rain sounds, and cooler temperatures. It reflects how the human body adapts to environmental changes. So, if you find yourself yawning on a rainy day, know that it’s simply your body responding as nature intended.

References

• Bangkok Hospital. (2019). Why do we feel sleepy when it rains?
• Faculty of Medical Technology, Mahidol University. (2021). White Noise: A sound that helps you sleep better

Translated by : Page Admin