There's nothing worse than waking up on a gloomy day. It's dark, rainy, and hardly conducive for going to work.
The reason for your morning struggle is, in fact, the weather. Our bodies rely on sunlight to signal our internal clocks that it's time to wake up. Without bright morning sunlight to kickstart our day, we'll feel lethargic and down. It's not the rain per se making us want to stay in bed and snuggle under the covers, but the lack of light we're reacting to.
Light inhibits the secretion of melatonin, the hormone that makes us sleepy. When there are overcast skies, our bodies will continue producing melatonin, even after our alarm clocks go off. Serotonin, which enhances mood, is also produced in the presence of sunlight. When there is less sunlight, serotonin production is reduced.
There are other non-hormonal reasons why we're extra tired on rainy days. For one, the earthy smell of rain is soothing. The musky scent is produced when a substance called geosmin interacts with plant oils present in the soil. The oils are secreted during dry periods to prevent the seeds from germination. Another relaxing smell is that of ozone, which appears after a thunderstorm. Ozone is a molecule made of three oxygen atoms, and is generated when lightening interacts with the air. This aroma resembles that of freshly laundered sheets, which can induce sleep.
Rain sounds are also quite comforting. The rhythmic pitter-patter of rainfall is considered "pink noise," which is a category of relaxing background noise. Pink noise has been shown to improve the quality of sleep by muffling out outside noises and decreasing brain activity.
Rain definitely makes it harder to wake up, but it doesn't have to keep you sleepy all day. Try eating a healthy breakfast to energize you or hit the gym, if you can. Another way to combat the negative effects of rainy mornings is to open the blinds and give your home as much exposure as possible to natural light. If you know it's going to rain the night before, sleep with your curtains or blinds open to allow any bit of light to seep through.