When defining what sleep is, it is imperative to mention the nervous system as it is a regulatory function of the nervous system. Therefore, animals and human beings require sleep as a vital part of their life and growth. Have you ever wondered if your plants sleep? Plants cannot sleep in the typical meaning of the word sleep because they do not have a central nervous system. However, plants also follow the earth’s day/night 24hour cycle as well as other cycles such as seasonal variations. Plants have a circadian rhythm just like human beings do. The circadian cycle in human beings controls the sleep-wake cycle. During the day, our bodies stay awake while during the night, melatonin is released which causes drowsiness. Plants have been shown to also follow a circadian rhythm even when kept indoors in constant light conditions. These senses also inform them of seasonal changes, i.e. when the days start to get shorter during the fall, plants understand that winter is nearing and they thus begin to go into dormancy. The circadian rhythm in plants has also helped certain other plants to avoid predators by estimating the time they attack them and releasing harmful chemicals to ward them off.
Despite the fact that plants do not typically go to sleep, due to the circadian rhythm they follow, they enter a kind of rest mode at night. During the day, photosynthesis takes place in plants by taking in Carbon dioxide, water, and light from the sun to produce sugars and Oxygen which is released back into the atmosphere. When the sun goes down, plants shut down photosynthesis and can therefore make no more food for the day. At this point, they break down the sugars made during the day and focus on metabolism and rest.
Do plants need sleep? Yes, plants do need sleep. Plants do not exactly sleep; they however do go into rest mode when nighttime rolls around in order to focus on metabolism and growth. This function is regulated by the plant’s circadian rhythm which is activated to release auxins, which regulate growth and development, at night.
What Time do Plants Sleep?
Now that we know that plants do not typically go to sleep like other living things, let us discuss the rest cycle of plants. Plants follow the earth’s day/night cycle and we can therefore say that they rest during the night like human beings and animals. During the day, the plants utilize the light they get from the sun and make food through the process of photosynthesis. Plants, unlike most other living things, cannot move in search of food, therefore, during the day, it is beneficial for most plants to take full advantage of the sun and make food. It is therefore not advantageous for plants to rest during the day. There are however plants that close their stomata during the day and perform photosynthesis through another method known as Crassulacean Acid Metabolism (CAM).
Scientists believe that plants calculate how to divide their stored energy by the number of hours the night has in order to ensure they have enough stored nutrients for the night. Therefore, they adapt to different seasons of the year and some thrive when the nights are longer in the winter with others doing better when the nights are shorter in the summer. In order to sense the cycles of night and day, plants use photoreceptor proteins. These proteins act like a light switch and enable the plant to smoothly transition from the day’s activity of photosynthesis to the night’s activity of respiration.
How Long do Plants Sleep?
The amount of time a plant requires in the dark or in the light to grow, also known as photoperiodism, determines how many rest hours a plant needs. According to this definition, plants are divided into long-day plants and short-day plants. Long-day plants refer to plants that grow best when the days are long and the nights are short, like during the summer season. Most fruits and vegetables fall under this category like dill, spinach, rye, and hibiscus amongst others. These plants need less than 12 hours of darkness for optimum growth. Short-day plants on the other hand are plants that grow better when the days are short and the nights are long, like in winter. Examples of plants that fall in this category are the Flaming Katy plant (Kalanchoe blossfeldiana) and the Christmas cactus.
Conversely, when choosing a houseplant, it is important to choose one that prefers darkness because houses typically receive less light than the outside, and thus long- day plants would not do too well in the house. In situations where accessing natural light is difficult, I would recommend this 75W LED Indoor Growth Light for Indoor plants that can provide artificial light for your plants in case of a dimly lit house. You can read more on it here.
Can Plants Sleep with Lights on all Night?
Artificial light also exerts a significant effect on plants therefore, even in situations where plants receive low natural light, artificial lights also need to be switched off as plants still require hours in complete darkness. A few nights with the lights on would not cause too much harm; however, prolonged exposure to constant artificial light can negatively affect the growth of plants. Some of the signs of prolonged exposure to light include; significant flowering problems, poor bud development, wilting of leaves, and burn patches. As mentioned above, the growth cycle of a plant is determined largely by the presence and absence of light therefore, having the lights on all the time will negatively impact this growth cycle.
Most artificial lamps emit heat and thus leaving them on throughout increases the temperature of the plants’ environment. This has a negative impact on the plant as it begins to release water to cool itself down and this can dehydrate the plant resulting in burn patches on the leaf and crisp burnt edges on the tips of the leaf. A state of dehydration can also affect the plant’s ability to make food and thus can starve the plant which will eventually kill it. It is therefore important to switch off the lights and give the plants some dark time.
Artificial lights are however not harmful to the plant if used in moderation. One such type of light is this 50W Plant Grow Light for Indoor Plants whose light spectrum is sun-like. You can read more on it here.
Do Plants Sleep During the Day or Night?
Following this discussion, we can therefore say that most plants rest at night because the absence of light is what prompts them to switch from the day’s activities to the night’s activities. They sleep at night because that is when photosynthesis ceases and respiration kicks in. Respiration is defined as the process by which plants make their own energy by taking in Oxygen and giving off Carbon dioxide, water, and energy.
During the day, the effect of the sun prompts the photosynthetic process in plants and thus they cannot rest during the day. It has also been observed that plants experience a growth spurt right before daybreak as this is when they grow the most. Using their photoreceptors, they can sense when it is almost daybreak and release the necessary growth hormones. This also proves that plants rest at night as plants grow when they are in rest mode.
Final Thoughts
Plants, just like most other living things, need regular rest. Plants do not typically sleep but they do rest and follow the earth’s night/day cycle. A little rest is important for the plants because when the sun goes down and the plant is in the dark, photosynthesis is halted in the plant. At this point, the plant breaks down the sugars it manufactured during the day and it is during this metabolic process that the plant grows and blooms better. Keeping a plant in the light at all times is not dangerous to the plant; it encourages faster and constant growth, it, however, beings to show signs of exhaustion after a while such as poor blooming and poor bud development.
Therefore, as we choose what houseplant to keep, it is important to consider its light cycle to offer it optimal growing conditions. If considering artificial light for the plants as the primary source of light, I would recommend this 4- Head Goose- Neck Plant Light for indoor plants. It is however important to remember to turn off the lights at night even as you yourself turn in for the night. Read more about this lamp here.