Micellar casein is the slow-digesting milk protein many lifters take before sleep. The idea is simple: a steady supply of amino acids overnight, while you are not eating. This guide covers what the position stands actually say, how much to take and who is likely to benefit.
What the research says
The International Society of Sports Nutrition (ISSN) published its protein and exercise position stand in 2017. As summarised by NutraIngredients, it suggests that 30-40 g of casein before bed may increase overnight muscle building and metabolic rate. Examine.com lists the same dose, taken about 30 minutes before sleep, and cites Res et al. (2012), who studied protein ingestion before sleep after exercise. It describes the effects as small but significant.
That last word matters. Examine also stresses that total daily calories, total daily protein and appropriate training matter much more than the timing of any one serving.
How casein fits into your daily protein
The ISSN stand suggests about 1.4-2.0 g of protein per kg of body weight per day for building and maintaining muscle, and about 0.25 g per kg per meal, or 20-40 g per serving. A pre-sleep casein shake is just one of those servings. If you already reach your daily target, it helps by spreading protein across the day. If you do not, fix the daily total first. Our guide to effective muscle-building foods covers whole-food options.
Who may benefit most
- People training hard in the evening who go many hours without food overnight.
- Lifters who struggle to reach their daily protein target.
- Anyone who likes a slow-digesting, filling option before bed.
Practical tips
- Mix 30-40 g of micellar casein with water or milk about 30 minutes before sleep.
- Count it toward your daily protein, not on top of it.
- Check the label for added sugar and third-party testing. See our supplement guide for what to look for.
Frequently asked questions
How much casein should I take before bed?
The ISSN protein position stand points to 30-40 g of casein before sleep. Examine.com reports the same range, taken roughly 30 minutes before bed.
Is casein before bed necessary to build muscle?
No. Total daily calories, total daily protein and consistent training matter far more. A pre-sleep dose is an optional extra for people who already hit those basics.
Can I use whey instead?
Whey digests faster, which is useful after training. Casein is the option the research on pre-sleep protein has focused on, so it is the better-studied choice for the hour before bed.
References
- NutraIngredients: ISSN publishes position stand on protein and exercise (2017)
- International Society of Sports Nutrition Position Stand: protein and exercise
- Examine: Is it better to take casein before sleeping?
- Jäger R et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. PubMed 28642676
- Res PT et al. (2012). Protein ingestion before sleep improves postexercise overnight recovery. Med Sci Sports Exerc. PubMed 22330017
General information, not medical advice. Last updated 27 October 2026. This post replaces our older article on micellar casein.
