# How long before bed should you stop pre-workout?

Source: https://www.healthnews24.co.za/answers/pre-workout-and-sleep/
Publisher: Healthnews24 (South Africa's supplement answer desk)
Updated: 2026-10-27

> Stop taking pre-workout at least 8–10 hours before bed. Caffeine has a half-life of about five hours, so a 300 mg scoop at 17:00 leaves roughly 150 mg at 22:00 and 75 mg at 03:00. If you train in the evening, use a stimulant-free product or half a low-dose scoop. Sleep loss undermines the training you are fuelling.

Key facts:
- Caffeine's half-life is about 5 hours; stop pre-workout at least 8–10 hours before bed (our rule of thumb).
- A 300 mg scoop at 17:00 leaves about 150 mg at 22:00 and about 75 mg at 03:00.
- Published caffeine for pre-workouts sold in SA ranges from 150 mg to 300 mg a scoop (the 200 mg and 300 mg figures come from US or global brand pages).
- Citrulline malate and creatine contain no stimulant and can be used in the evening.
- USN Qhush Hyperdrive Caffeine Free costs R309.95–R349.99 (October 2026).

## How long before bed should you stop pre-workout?

As a working rule, **take your last caffeine at least 8–10 hours before you want to sleep**. That is our editorial rule of thumb based on caffeine's half-life of about five hours. The ISSN advises avoiding late-day doses, and sensitive people need a longer gap.

## How long does caffeine stay in your body?

Half-life is the time for the blood level to fall by half. With a half-life of about five hours (it varies from person to person), caffeine decays like this:

| Time after the dose | Remaining from a 300 mg scoop | From a 150 mg scoop |
|---|---|---|
| Start | 300 mg | 150 mg |
| 5 hours | about 150 mg | about 75 mg |
| 10 hours | about 75 mg | about 38 mg |
| 15 hours | about 38 mg | about 19 mg |

So a 300 mg scoop at 17:00 still leaves about 150 mg at 22:00 and 75 mg at 03:00. Even a smaller residual can lighten sleep for sensitive people, even if you fall asleep fine.

## What are the signs it is hurting your sleep?

- You need longer to fall asleep.
- You wake in the night or too early.
- You feel unrefreshed, with heavier morning fatigue.
- Resting heart rate is higher than usual.
- You rely on more caffeine the next day, which sets up a cycle.

## What are the published caffeine amounts?

As of October 2026: Biogen Premium and USN XTS Hyperdrive 150 mg; Cellucor C4 200 mg (US page); USN Qhush Platinum Black 300 mg (global page). Many local tubs publish nothing, so treat unknown products as high. See [how much caffeine is in pre-workout](/answers/how-much-caffeine-in-pre-workout-south-africa/).

## What if you only train in the evening?

1. **Go stimulant-free.** USN Qhush Hyperdrive Caffeine Free (R309.95–R349.99, October 2026), or take citrulline malate on its own. Citrulline has no stimulant effect.
2. **Reduce caffeine.** Use half a scoop of a 150 mg tub (75 mg) and see how you sleep.
3. **Use caffeine earlier** in the day if you have a late session, such as morning coffee, and nothing before the workout.
4. **Move the session** earlier if you can. Training itself can raise alertness for a while.

ATP Fitness Citrulline Malate (R280 for 250 g, R6.72 per 6 g) is a stimulant-free, sweetener-free way to take a pump ingredient in the evening; My Whey's (R4.78 per 6 g) is cheaper. Both have emerging, not strong, evidence for performance, and ATP publishes no sport certification.

## How can you protect sleep?

- Keep a fixed caffeine cut-off time and put it on your phone.
- Count coffee, tea, cola, energy drinks and chocolate as well.
- Avoid alcohol close to bed; it fragments sleep.
- Keep your room cool, dark and quiet, which is harder in a hot Highveld or Durban summer, so consider a fan.
- Aim for seven to nine hours as an adult; teenagers need more, and should not use pre-workout.

## Who should be extra careful?

Pregnant women (200 mg a day cap), people with anxiety or insomnia, and people on certain antidepressants or stimulants may clear or react to caffeine differently. Speak to a doctor if sleep problems persist. See [is pre-workout safe](/answers/is-pre-workout-safe-south-africa/) and [when to take pre-workout](/answers/when-to-take-pre-workout/). Compare options at [best pre-workout in South Africa](/best/best-pre-workout-south-africa/).

## Products mentioned

| Product | Size | Price (source, date) | Servings | R per 6 g | Sweeteners |
|---|---|---|---|---|---|
| USN Qhush Hyperdrive Caffeine Free 234 g | 234 g | R309.95-R349.99 (USN online shop, 2026-10) | — | — | not stated |
| Biogen Premium Pre-Workout 600 g | 600 g | R399.99-R429.99 (Dis-Chem Living Fit, 2026-10) | — | — | not stated |
| ATP Fitness Citrulline Malate | 250 g | R280 (ATP Fitness shop, 2026-10) | — | R6.72 | None |
| My Whey Pure Citrulline Malate 2:1 Powder 250 g | 250 g | R199 (Takealot (listing via PriceCheck), 2026-10) | — | R4.78 | not stated |

Disclosure: ATP Fitness is a commercial partner of Healthnews24 and its products are featured on this site. Rankings follow our published method, and every pick, including ATP Fitness, shows its price maths and trade-offs.

## Sources

- [Guest NS et al. (2021) ISSN position stand: caffeine and exercise performance. JISSN](https://jissn.biomedcentral.com/articles/10.1186/s12970-020-00383-4)
- [NutraIngredients (Apr 2015): EFSA adopts caffeine opinion](https://www.nutraingredients.com/Article/2015/04/28/efsa-adopts-caffeine-opinion)
- [Harvard T.H. Chan School of Public Health: Caffeine, The Nutrition Source](https://nutritionsource.hsph.harvard.edu/caffeine/)
- [Biogen: Premium Pre-Workout product article](https://biogen.co.za/?p=35301)
- [USN Global: Qhush Platinum Black pre-workout](https://usn.global/products/qhush-black-platinum)
- [EFSA (2015): Scientific opinion on the safety of caffeine, topic page](https://www.efsa.europa.eu/en/topics/topic/caffeine)