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Why Use Overnight Protein?

Our body gets stronger and we gain in fitness by putting ourselves under stress during training. Sleep is the time when our body responds to this stress and makes the physiological adaptations we are looking for. For optimal protein feeding to support the growth and maintenance of lean muscle mass, 20-25g of protein every 3-4 hours is recommended(1). This can be difficult to maintain while you’re asleep! Whey and Soy protein digest quickly at 8-10 grams per hour, so If you used these before bed you would have to feed during the night to maintain a continued supply of amino acids, the building blocks of protein, which of course is not ideal! In comparison, milk protein (found in SiS Overnight Protein) is slow digesting, continuously feeding the muscles as you sleep.

A protein feed before bed is a good way to ensure you hit your target intake, depending on your training goal, gender and activity level. If lean muscle mass is your goal, the prolonged rise in amino acids in the blood stream will help to stimulate the production rate of new muscle protein. If you have been doing a high volume of endurance training, it is often difficult not to end up in negative energy balance for that day, so taking in protein overnight will help to maintain lean muscle mass and stop you from breaking down your lean muscle tissue for energy.

What makes Overnight Protein different?

Milk is made up of approximately 20% whey protein, which is released quickly. The other 80% is casein, which is released much more slowly, at around half the rate of whey protein isolate at 3.5 grams per hour(2). The milk protein isolate found in SiS Overnight Protein is obtained by removing the fat and carbohydrate, resulting in a lean, slow release protein.

Why not just drink a glass of milk?

Milk contains a high level of carbohydrate as the dairy sugar lactose, which you may want to avoid just prior to bed depending on your fitness goal. This makes milk protein isolate the ideal choice for a pre-bedtime protein feed that should last you well into the night, without any additional unwanted calories from carbohydrate or fat. This is why it is the main ingredient in SiS Overnight Protein.

What does the research say?

Milk protein isolate (the key component of SiS Overnight Protein) was actually found to be superior in supporting lean muscle mass gains compared to micellar casein alone in a recent study due to it’s higher leucine content, maintaining muscle protein synthesis for longer(3). This makes SiS Overnight Protein the ideal formulation to support your muscle rebuild and recovery throughout the night.


  1. Witard, O. C., Jackman, S. R., Breen, L., Smith, K., Selby, A., & Tipton, K. D. (2014). Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. The American Journal of Clinical Nutrition, 99(1), 86-95.
  2. Bilsborough, S., & Mann, N. (2006). A review of issues of dietary protein intake in humans. International Journal of Sport Nutrition and Exercise Metabolism, 16(2), 129.
  3. Babault, N., Deley, G., Le Ruyet, P., Morgan, F., & Allaert, F. A. (2014). Effects of soluble milk protein or casein supplementation on muscle fatigue following resistance training program: a randomized, double-blind, and placebo-controlled study. Journal of the International Society of Sports Nutrition, 11(1), 1.
Written By

Ted Munson (Performance Nutritionist)

Ted is a Performance Nutritionist here at Science in Sport.