People must have sleep, animals need to sleep. But what about plants – do plants need sleep?
While definitions of ‘sleep’ differ, plants, like humans and animals, also tune into a 24-hour circadian rhythm, which requires them to have light and also the absence of light, for optimal health.
The Portulaca Sun Jewels (Portulaca oleracea) below illustrate the point well. These photos were taken within the same 24 hours. The photo at the top was taken very early morning, and the plant appears to be ‘asleep’, but once the sun is out bursts into bloom.
What is happening when plants ‘sleep’?
Like humans, plants also have critical processes underway during the night, even though they may appear to have shut down.
When plants are ‘sleeping’ they produce the hormone auxin, which controls their growth and development. It is also when they metabolise the energy taken in through the day.
What happens when plants are exposed continuously to light and cannot benefit from ‘sleep’ time?
Although it is possible for plants to live with light present 24 hours per day, this is not recommended by many including Tammy Clayton of the Garden Culture Magazine, who advises poor flowering, then fruiting, and declining health comes as a result of insufficient absence of light.
There are mixed results according to different types of plants, however negative effects such as limited or reduced plant grown and productivity, and leaf damage and yellowing as a result of a lack of chlorophyll are reported, as per this study
published by Global Science Books.
In conclusion, plants, like humans, have a natural cycle where it appears not much is going on, but in fact critical processes are in motion. In order to thrive, like humans, the majority of plants require a ‘sleep’ time just like we do!