Sleeping in springtime, oblivious of dawn explained
You probably have the experience that in the spring, you often feel tired when waking up in the morning and lose momentum during the day. What causes this?
Though the temperature starts to rise, spring is also a season with alternate cool and warm weather, brought about by the occasional passage of a cold front from the north. Because of the weather changes, our body has to constantly regulate the internal temperature. This requires more energy and makes us feel tired and sleepy. It is also humid and foggy in the spring. Fog forms when the moist and warm air from the south crosses the relatively cool waters in the South China Sea. The moisture blocks evaporation of sweat from our body, making things worse. Furthermore, the mixing of cold and warm air brings continuous rain and overcast skies. No wonder some people feel depressed and become inactive.
After the Spring Equinox, the Sun originally overhead in the southern hemisphere moves north gradually. Days become longer and nights shorter in the northern hemisphere. For some people this may mean a shorter sleep and greater difficulty in getting up from bed.
Therefore, it is important to get sufficient sleep and exercises in the spring, for a sound body to adjust to the march of seasons.