PLANTS SLEEP AT NIGHT
We are always asked not to disturb plants at night as they are sleeping. Do they really sleep?
Yes, they do sleep but not in the way we do as they lack Central Nervous System. They exhibit circadian rhythm for sleeping or life processes.
Circadian rhythm also referred as body clock is a 24-hour cycle adapted by our body to sleep, rise, eat etc. regulating many physiological processes. It is affected by external factors like sunlight and temperature.
During daytime plants carry out photosynthesis (process of making food by plants using sunlight) and during dusk/ at night when there is no sunlight, photosynthesis ceases and only respiration continues. This can be considered as sleeping.
Some plant species even fold their leaves at night. For example:
• Mimosa pudica (touch-me-not plant) leaves droop in response to darkness and reopen with daylight.
• Prosopis juliflora (mesquite) fold their leaves during night.