Why do I feel tired after taking collagen?

Why Do You Feel Tired After Taking Collagen?

It’s not uncommon to wonder why you’re feeling sluggish after starting a new supplement—and if you’ve recently added collagen to your routine, you might be blaming it for that afternoon dip in energy. The truth is, collagen itself isn’t known to cause fatigue for most people. In fact, many turn to it for its potential benefits to skin, joints, and hair. But there’s a twist: one of collagen’s key amino acids, glycine, could be the reason you're feeling a bit drowsy.

Glycine is found in high amounts in collagen, and research suggests it may have calming effects on the nervous system. Some people actually take collagen at night on purpose because of this. Studies have shown that glycine can help lower core body temperature and improve sleep quality when taken before bed—similar to how a warm bath might make you feel sleepy. So if you're taking your collagen powder in a morning smoothie and suddenly feel like napping, your body might just be responding to this natural compound.

That said, individual reactions vary. While some notice a subtle calming effect, others feel nothing at all. If drowsiness persists or interferes with your day, try shifting your dose to the evening. You might find it supports better sleep instead of slowing you down during the day.

Feeling tired after collagen isn’t typical, but it’s not unheard of—especially if you're sensitive to glycine. Listen to your body, adjust the timing, and you might just turn that fatigue into a better night’s rest.