Quick Answer: CBD (cannabidiol) affects your body through the endocannabinoid system, producing anti-inflammatory, anxiety-reducing, and mildly sedative effects. Common side effects include drowsiness, digestive changes, and dry mouth. The most serious concern is drug interactions, as CBD competes with many medications for liver processing. Long-term effects beyond a few months remain largely unstudied.
In This Guide
Reading Time: 10 minutes
Everyone talks about what CBD does for you. Fewer people talk about what it does to you. Those are related but different conversations, and both matter if you are thinking about adding CBD to your routine.
At Mattress Miracle, we hear about CBD from customers regularly. "I take CBD for sleep." "My physiotherapist suggested CBD for pain." "I tried it and felt nothing." All of these responses are plausible because the effects of CBD depend on dose, delivery method, your individual biology, and what you are taking it for.
Here is what the research tells us about how CBD actually works in your body.
How CBD Moves Through Your Body
Understanding the effects of CBD starts with understanding how it gets from the bottle into your system. The route matters because it changes how much CBD your body actually absorbs and how quickly you feel anything.
Sublingual (under the tongue)
CBD oil held under the tongue for 60 to 90 seconds absorbs through the mucous membranes directly into the bloodstream, bypassing the digestive system. Onset: 15 to 45 minutes. Bioavailability: roughly 13 to 19% according to a review in Frontiers in Pharmacology.
Oral (swallowed capsules, edibles, gummies)
When swallowed, CBD passes through the digestive system and liver before reaching the bloodstream. This "first-pass metabolism" means the liver breaks down a significant portion before it ever reaches systemic circulation. Onset: 30 minutes to 2 hours. Bioavailability: roughly 6 to 13%, though taking CBD with fatty food can increase absorption.
Inhaled (vaping, smoking)
Inhaling CBD delivers it directly to the lungs and into the bloodstream almost immediately. Onset: 2 to 5 minutes. Bioavailability: up to 31%. However, Health Canada and the CDC both note respiratory risks associated with vaping, including potential lung injury.
Topical (creams, balms)
Applied to the skin, CBD affects local receptors without significant systemic absorption. This means topical CBD may help with localized pain or inflammation but is unlikely to affect sleep, anxiety, or other systemic functions.
| Delivery Method | Onset Time | Bioavailability | Duration | Best For |
|---|---|---|---|---|
| Sublingual oil | 15-45 min | 13-19% | 4-6 hours | Sleep, anxiety |
| Capsules/edibles | 30 min - 2 hrs | 6-13% | 6-8 hours | Sustained effect |
| Inhaled | 2-5 min | Up to 31% | 2-3 hours | Rapid relief (with lung risks) |
| Topical | 15-45 min locally | Minimal systemic | 2-4 hours | Localized pain |
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Positive Effects: What Research Supports
CBD interacts with your endocannabinoid system, serotonin receptors, and vanilloid receptors. The result is a range of effects that vary by dose and individual.
Anxiety reduction
This is perhaps the best-supported effect outside of epilepsy treatment. A review in Neurotherapeutics (Blessing et al., 2015) found consistent evidence that CBD reduces anxiety in both animal models and human studies. The mechanism appears to involve serotonin 5-HT1A receptor activation, similar to how some prescription anti-anxiety medications work but through a different pathway.
Shannon et al. (2019) tracked 72 adults and found 79.2% reported decreased anxiety scores within the first month.
Anti-inflammatory action
A comprehensive review in Antioxidants (2020) documented CBD's anti-inflammatory and antioxidant properties at the cellular level. CBD appears to reduce inflammatory markers like cytokines and inhibit oxidative stress. For conditions involving chronic inflammation, like arthritis or fibromyalgia, this could help explain why some people report relief.
Pain modulation
CBD influences vanilloid receptors (TRPV1), which are involved in pain perception and body temperature regulation. Real-world data from a Canadian medical cannabis clinic published in the Journal of Cannabis Research (2021) found that CBD-rich treatments provided meaningful pain relief for patients with moderate to severe symptoms.
That said, Harvard Medical School has cautioned that standalone evidence for CBD as a pain treatment is "little or weak." It likely works better as part of a broader approach.
Nausea and appetite
CBD has documented antiemetic (anti-nausea) properties. The Mayo Clinic notes it may affect appetite in both directions, some people experience increased hunger, others decreased. This variability seems to depend on individual factors and dose.
Side Effects You Should Know About
The CDC identifies several common side effects of CBD that are worth knowing before you start.
| Side Effect | How Common | What to Know |
|---|---|---|
| Drowsiness/fatigue | Very common | Dose-dependent. Lower doses may actually be mildly stimulating. |
| Diarrhoea | Common | More frequent with higher doses. Often resolves as body adjusts. |
| Appetite changes | Common | Can increase or decrease. Varies by individual. |
| Dry mouth | Common | CBD affects saliva production through cannabinoid receptors in salivary glands. |
| Low blood pressure | Occasional | May cause lightheadedness when standing quickly. |
| Liver enzyme elevation | Rare (high doses) | Documented with pharmaceutical-grade CBD (Epidiolex) at very high doses. |
Talia, Showroom Specialist: "I have had customers mention that CBD makes them drowsy the next morning. In those cases, I always ask about their overall sleep setup. Sometimes the drowsiness is the CBD, sometimes it is a mattress that is not letting them get proper deep sleep, and sometimes it is both. We cannot diagnose the CBD side, but we can definitely help with the mattress side."
Drug Interactions: The Serious Part
This section is not optional reading. If you take any prescription medications, this is the most important part of this article.
CBD is metabolized by the cytochrome P450 enzyme system in your liver. Specifically, it interacts with CYP3A4 and CYP2C19, the same enzymes responsible for processing a long list of common medications.
When CBD competes for these enzymes, it can increase the concentration of other drugs in your bloodstream, sometimes to dangerous levels. The Mayo Clinic and CDC both highlight this concern.
Medications That May Interact with CBD:
- Blood thinners (warfarin, heparin): CBD can increase bleeding risk
- Heart medications (amiodarone, certain beta-blockers): CBD can alter drug levels
- Anti-epileptics (clobazam, valproate): Increased side effects possible
- Immunosuppressants (tacrolimus, cyclosporine): Altered drug metabolism
- Antidepressants (SSRIs, SNRIs): Potential serotonin-related interactions
- Sedatives and sleep aids: Compounded drowsiness effects
This is not a complete list. If you take any prescription medication, speak with your pharmacist before using CBD. This is not a suggestion. It is a safety necessity.
Special populations
Pregnant and breastfeeding women: The CDC and Health Canada both advise against CBD use during pregnancy and breastfeeding. Animal studies have shown negative effects on fetal development at high doses, and CBD can pass through breast milk.
Children and adolescents: Outside of prescription use for epilepsy under medical supervision, CBD use in children is not recommended. Safety data for this age group is extremely limited.
Older adults: Increased sensitivity to drowsiness and blood pressure effects, combined with a higher likelihood of taking multiple medications, means older adults should be particularly cautious and consult their healthcare team.
Effects on Sleep Specifically
Since sleep is what we know best at Mattress Miracle, let us look at how CBD's effects relate specifically to rest.
CBD's sleep effects are primarily indirect. Rather than sedating you the way a prescription sleeping pill does, CBD appears to address some of the barriers to sleep:
- Reducing anxiety that keeps your mind racing at bedtime
- Easing pain that makes it hard to find a comfortable position
- Modestly improving sleep efficiency (the percentage of time in bed that you actually spend sleeping)
A 2024 pilot trial in the Journal of Clinical Sleep Medicine found that 150 mg of nightly CBD improved sleep efficiency after two weeks. Participants also reported feeling more alert upon waking. However, overall insomnia severity did not differ significantly from placebo.
Research from Nutrients (2023) found that eight weeks of daily 50 mg CBD improved sleep quality and immune cell activity in healthy younger adults.
Our Honest Perspective: We have been helping Brantford families sleep better since 1997, and in our experience, the most impactful change most people can make for their sleep is not a supplement. It is their mattress. A study in the Journal of Chiropractic Medicine (Jacobson et al., 2008) found that a new, properly supportive mattress significantly reduced back pain and improved sleep quality. That does not mean CBD is useless, it means the foundation matters more than what you stack on top of it.
If you are considering CBD for sleep, make sure the basics are covered first. A properly supportive mattress, a cool room (16-19 degrees Celsius per the Canadian Sleep Society), a good pillow, and consistent sleep times will do more for most people than any supplement.
What We Still Do Not Know
Honesty requires acknowledging the gaps. Here is what remains unclear about the effects of CBD:
- Long-term safety. Most studies have tracked participants for weeks to months. We do not have robust data on what daily CBD use does over years.
- Optimal dosing. Effective doses in studies range from 25 mg to 1,500 mg daily. There is no established standard dose for any condition (outside of the Epidiolex prescription).
- Hormonal effects. Some animal studies suggest CBD may affect reproductive hormones. Human data is insufficient to draw conclusions.
- Effects on developing brains. Long-term impacts on adolescent brain development are unknown.
- Product consistency. Outside of licensed Canadian retailers, CBD product quality varies significantly. A 2017 study in JAMA found that only 31% of tested CBD products contained the amount of CBD claimed on the label.
The World Health Organization has stated that pure CBD shows "no effects indicative of any abuse or dependence potential" and no evidence of "public health related problems." That is reassuring. But "no evidence of problems so far" is not the same as "proven safe long-term." That distinction matters.
Brad, Owner, 40+ years of experience: "I always tell people: we know exactly what a good mattress does for your sleep. We have decades of research and nearly 40 years of watching customers come back and tell us they are sleeping better. With CBD, the picture is still developing. That does not mean it is bad. It means you should approach it with realistic expectations."
Sources
- Blessing, E.M. et al. (2015). Cannabidiol as a Potential Treatment for Anxiety Disorders. Neurotherapeutics, 12(4), 825-836.
- Shannon, S. et al. (2019). Cannabidiol in Anxiety and Sleep: A Large Case Series. The Permanente Journal, 23, 18-041.
- CDC. About CBD. Cannabis and Public Health. cdc.gov.
- Health Canada. Science Advisory Committee on Health Products Containing Cannabis. canada.ca.
- Mayo Clinic. CBD: Safe and effective? mayoclinic.org.
- PMC (2020). Cannabidiol Adverse Effects and Toxicity.
- Bonn-Miller, M.O. et al. (2017). Labeling accuracy of cannabidiol extracts. JAMA, 318(17), 1708-1709.
- Nutrients (2023). Eight Weeks of Daily CBD Supplementation Improves Sleep Quality, 15(19), 4173.
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We are a family-owned mattress store in Brantford, helping our community sleep better since 1997. Come try mattresses in person and get honest, no-pressure advice.
441 1/2 West Street, Brantford, Ontario
Call 519-770-0001Frequently Asked Questions
How long does it take to feel the effects of CBD?
It depends on the delivery method. Sublingual oils (held under the tongue) typically take 15 to 45 minutes. Edibles and capsules take 30 minutes to 2 hours because they pass through the digestive system first. Inhaled CBD takes effect within minutes but may carry respiratory risks. For sleep purposes, most people take CBD oil 30 to 60 minutes before bed.
Can CBD make you feel tired during the day?
Drowsiness is one of the most commonly reported side effects of CBD, particularly at higher doses. The CDC lists tiredness as a primary side effect. If you experience daytime drowsiness, reducing the dose or taking CBD only in the evening may help. Some people find that lower doses actually have a mildly alerting effect rather than a sedating one.
Does CBD show up on a drug test?
Pure CBD should not trigger a positive drug test, as standard tests screen for THC. However, many CBD products contain trace amounts of THC (up to 0.3% is legal). With heavy daily use, these trace amounts could theoretically accumulate enough to produce a positive result. If drug testing is a concern, look for CBD isolate products rather than full-spectrum options, and buy from licensed Canadian retailers whose products are tested for THC content.
Is CBD safe to take every night for sleep?
Short-term daily use appears safe for most healthy adults based on current evidence. The World Health Organization noted that CBD exhibits no effects indicative of abuse or dependence potential. However, long-term safety data beyond a few months is limited. Health Canada recommends consulting a healthcare provider before daily use, especially if you take other medications. For ongoing sleep issues, addressing your sleep environment is a more sustainable foundation.
What are the most serious risks of CBD?
The most significant risk is drug interactions. CBD competes for the same liver enzymes that process blood thinners, heart medications, anti-epileptics, and immunosuppressants. High doses of pharmaceutical-grade CBD (Epidiolex) have been associated with liver enzyme elevation. Pregnant and breastfeeding women are advised to avoid CBD based on animal studies showing negative effects on fetal development.
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We are located at 441½ West Street in downtown Brantford. Free parking available. Our team does not work on commission, so you get honest advice based on your needs.
Mattress Miracle , 441½ West Street, Brantford, ON · (519) 770-0001
Hours: Monday–Wednesday 10am–6pm, Thursday–Friday 10am–7pm, Saturday 10am–5pm, Sunday 12pm–4pm.