Did you know that maintaining a separate morning and night-time skincare routine can be a total game-changer for your skin? Some ingredients are simply formulated to work best at night plus, they get the time to really sink in and repair your skin while you catch up on your beauty sleep. Peptides and glycolic acid are two ingredients that have creating a buzz in the world of beauty lately. Before you add them to your routine, here's exactly when you should be using them and why. Peptides, which are short-chain amino acids that boost proteins like elastin and keratin, can be applied at any time of the day. For maximum effectiveness, you should make sure that they have a spot in both your day and night-time skincare routine. Glycolic acid, much like retinol, belongs exclusively in your night-time regime, thanks to the fact that it increases your skin's photosensitivity (read: apply sunscreen the next morning). PS: If you've just introduced glycolic acid into your skincare routine, you should slowly work up to using it daily to prevent any potential irritation from occurring.