Herbs that may have awakening effects should never be taken at nighte. Some critical supplements are known for their awakening properties and other sleep-bothering effects, such as enhancing energy and stimulating brain functions.

Ashwagandha
Indian ginseng, commonly known as ashwagandha, is an important medicinal plant, and its extract has many bioactive compounds. Many ashwagandha products have antioxidant, anti-inflammatory, and immunomodulatory properties. So, it is used to prevent and get more progress on many diseases, such as arthritis, impotence, amnesia, anxiety, cancer, neurodegenerative and cardiovascular diseases, and others (1).
Ashwagandha reduced stress and anxiety levels. And this can reduce sleeplessness, fatigue, and even serum cortisol (a stress hormone). This adaptogenic herb helps reduce stress and anxiety. For this reason, many can improve their energy levels and reduce their feelings of fatigue over time.
Even though research is limited, a few clinical trials suggest that ashwagandha extracts may help with sleep. People with this plant extract reported improvements in sleep quality in 72%, greater than the placebo group (2). These participants showed improvements in sleep efficiency, sleeping times, and latency. A systematic review and meta-analysis of five studies also reported that ashwagandha can promote sleep (3).
While often used for its adaptogenic properties to reduce stress, ashwagandha can cause increased alertness and insomnia in some individuals. Individuals might experience increased alertness or energy levels from ashwagandha, especially if taken in higher doses. Sometimes, this can lead to difficulties falling asleep or staying asleep. While ashwagandha is generally used to improve sleep and reduce stress, it can cause insomnia in some individuals. Monitoring your response and adjusting the dosage and timing can help mitigate this risk.

L-theanine
L-theanine is an amino acid commonly found in tea leaves, like green tea. Due to its calming effects, which promote relaxation without causing drowsiness, L-theanine is often used to improve sleep quality. However, in some cases, it may not be helpful for sleeping conditions.  
Some may have a unique response to L-theanine and may experience increased alertness or stimulating effects in the night. And because it originated from tea, a combination with caffeine or other stimulants is possible. In this case, L-theanine may enhance the alertness effects, making it much harder to fall asleep. L-theanine and caffeine are often used to improve focus and concentration, which might not be desirable close to bedtime. Higher doses of L-theanine could cause paradoxical effects. Instead of calming, higher levels of it often lead to severe restlessness. So it is wise to take L-theanine early enough in the day or close to bedtime. Appropriate doses and monitoring time are recommended if you want this supplement. Of course, no caffeine while taking this in the day.

Rhodiola Rosea
Rhodiola Rosea is a herb that helps the body manage stress and reduces mental and physical fatigue. Stimulation can interfere with the ability to fall asleep or stay asleep. This herb may help modulate the stress response by reducing cortisol and adrenaline, stress hormones. R. rosea may induce serotonine and dopamine activity to calm the mood. These properties directly affect the body’s stress response and indirectly contribute to better sleep.
However, like others, Rhodiola may also have stimulating properties that increase alertness and energy levels at night. So, for some individuals, especially if taken in higher doses or later in the day, this may cause insomnia or difficulty sleeping, especially if taken in the evening. Some individuals may experience increased restlessness, irritability, or overstimulation when taking it. Rarely reported, but R. rosea may cause gastrointestinal discomfort, such as stomach upset, nausea, or diarrhea, which may also disturb sleep quality.
Today, we all look at herbal supplements originally designed for good sleep. However, some individuals might suffer from insomnia because some of these products actually alert the body and may bother their sleep. Why don’t you check your sleeping supplements this time?

References
(1) Chapter 52 – Ashwagandha: Multiple Health Benefits. Nutraceuticals, 2016, Pages 717-733
(2) A randomized, double blind, placebo controlled study to evaluate the effects of ashwagandha (Withania somnifera) extract on sleep quality in healthy adults. Sleep Med 2020;72:28-36.
(3) Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One 2021;16:e0257843.