Does Choline Cause Drowsiness? The Science Behind Choline and Sleep

November 17, 2025 •

3 min read

According to a 2017 pilot study published in the journal Sleep Medicine, lower plasma choline levels were significantly associated with daytime sleepiness, suggesting that a deficiency—not excess—could be the real issue. This finding, among others, runs contrary to common misconceptions and raises an important question: does choline cause drowsiness, or is it a sign of something else entirely?.

Quick Summary

The idea that choline causes drowsiness is largely a misconception, with research indicating a deficiency may actually be linked to daytime sleepiness. Choline's role in the brain's cholinergic system can either promote wakefulness or contribute to a need for sleep, depending on dosage and individual chemistry.

Key Points

Drowsiness is Not a Direct Effect: Choline, as a precursor to the neurotransmitter acetylcholine, is generally associated with wakefulness and REM sleep, not sedation.
Deficiency May Link to Sleepiness: A 2017 study found that individuals with suspected sleep apnea and daytime sleepiness had lower, not higher, plasma choline levels.
Excessive Doses Have Side Effects: High supplemental doses above 3.5 grams per day can cause side effects like hypotension and dizziness, which might feel like fatigue.
Dietary Intake is Generally Safe: You are unlikely to get excessive amounts of choline from food alone; the risks are tied to large supplemental doses.
Choline Supports Cognitive Function: Healthy choline intake is associated with improved memory, mental function, and reduced anxiety.
Talk to a Doctor: Individuals with bipolar disorder should avoid high choline doses, and a healthcare provider should be consulted before starting new supplements.

The Choline-Acetylcholine-Sleep Connection

Choline is an essential, water-soluble nutrient vital for numerous bodily functions, particularly those related to the nervous system and brain health. Your body can produce a small amount, but most of it must come from your diet. A critical function of choline is its role as a precursor to acetylcholine, a neurotransmitter that plays a significant part in the regulation of the sleep-wake cycle.

The central role of acetylcholine is complex, influencing both states of wakefulness and REM (Rapid Eye Movement) sleep. Cholinergic neurons in the basal forebrain, for instance, are active during both alert wakefulness and REM sleep, stimulating cortical activity. This dual function explains why the relationship between choline and sleep isn't a simple 'on/off' switch. Rather than directly causing drowsiness, choline's effect is more nuanced and depends on a variety of factors, including the dosage and an individual's overall neurochemical balance.

The Impact of Dosage on Choline's Effects

Research indicates that moderate doses of choline are generally well-tolerated and support healthy brain function. However, the picture changes significantly with very high doses, typically achievable only through supplementation, not diet alone. Excessive choline intake, specifically over the Tolerable Upper Intake Level (UL) of 3,500 mg daily for adults, can lead to side effects. These effects, such as hypotension (low blood pressure), dizziness, and gastrointestinal upset, can indirectly manifest as lethargy or fatigue, which might be misinterpreted as drowsiness caused by choline itself. It is important to distinguish this fatigue resulting from side effects from a direct sedative effect.

Investigating the Counter-Intuitive Link to Sleepiness

Interestingly, some research points in the opposite direction. A study on subjects with suspected sleep apnea found that those experiencing excessive daytime sleepiness actually had lower plasma choline levels compared to non-sleepy individuals. While this is an observational study and cannot prove causation, it raises the possibility that an underlying metabolic or neurological issue causing sleepiness could also affect choline levels. Chronic sleep deprivation and the associated oxidative stress have been shown to impact choline plasmalogen levels, suggesting that poor sleep can itself disrupt choline metabolism. This creates a complicated feedback loop: poor sleep may reduce choline levels, while low choline might contribute to cognitive deficits that exacerbate a feeling of being 'sleepy' during the day.

Choline's Cognitive Benefits and Anxiety Reduction

Instead of being a sedative, choline is more often recognized for its role in cognitive enhancement and mood regulation. Adequate choline intake is necessary for optimal brain function, memory, and mood. Studies have linked higher choline intake to improved cognitive performance and a lower risk of dementia and Alzheimer's disease. Furthermore, research has suggested a correlation between higher choline levels and lower anxiety symptoms. This is consistent with the function of acetylcholine, which is crucial for attention, memory, and executive functions. A well-functioning cholinergic system promotes mental alertness, which is the opposite of drowsiness.

Choline's Impact on the Body: A Comparison


Aspect	Low Choline Intake (Deficiency)	High Choline Intake (Excess)
Mental State	Can lead to lethargy, brain fog, and fatigue.	May cause jitteriness or restlessness, not drowsiness.
Sleepiness	Associated with daytime sleepiness and fatigue.	High doses may cause fatigue due to hypotension or dizziness.
Gastrointestinal Effects	Unlikely to cause gastrointestinal issues directly.	Can cause stomachache, diarrhea, and vomiting.
Bodily Odor	Not a symptom.	May cause a fishy body odor.
Blood Pressure	Not typically associated with low blood pressure.	High doses can lead to a drop in blood pressure (hypotension).

Conclusion

In summary, the notion that choline causes drowsiness is a simplification that ignores the complex reality of its function. Far from being a sedative, choline is a critical nutrient for neurological function and alertness. While extremely high doses can produce side effects like dizziness and low blood pressure that might be perceived as fatigue, moderate intake actually supports cognitive function, memory, and mood regulation. Furthermore, scientific evidence suggests that a deficiency in choline may be associated with symptoms of sleepiness, particularly in individuals with pre-existing sleep disorders. For most people, ensuring adequate choline intake through a balanced diet is more likely to promote mental clarity than induce sleepiness. As with any supplement, consulting a healthcare professional is crucial before making significant changes to your intake, especially if you have pre-existing health conditions.

Frequently Asked Questions

While not a direct sedative, very high doses of choline supplements can cause side effects such as low blood pressure and dizziness, which may lead to feelings of fatigue or tiredness.

Choline's role in the brain is complex, supporting the function of acetylcholine, which is involved in both wakefulness and REM sleep. There is no definitive evidence to suggest it is a sleep aid, and some forms, like citicoline, have stimulating effects.

Choline is a precursor for the neurotransmitter acetylcholine, which influences the sleep-wake cycle. Cholinergic neurons are active during wakefulness and REM sleep, promoting cortical activation.

Low choline levels have been associated with a number of issues, including fatigue, cognitive problems, memory loss, and a higher risk of daytime sleepiness.

Different forms exist, including CDP-choline (Citicoline) and alpha-GPC. Research supports the cognitive benefits of citicoline, particularly for memory. The best form depends on individual needs and should be discussed with a healthcare provider.

Side effects, typically associated with high doses, include sweating, a fishy body odor, diarrhea, vomiting, and dizziness. Most people do not experience these when consuming choline from food alone.

Yes, research has linked adequate choline intake to improvements in cognitive performance, including verbal and visual memory, and has shown a correlation with lower anxiety symptoms.