So… you’ve got the perfect water bottle, you’ve downloaded an app to track your water intake, and you know your daily water goal. Now all you’ve got to do is drink, right?

Well, yes and no. There’s no harm in just meeting your daily hydration needs by drinking water willy-nilly throughout the day, perhaps drinking a bit more when you exercise. But there are certain times of day when you should be ramping up or cutting back your water intake. Here they are:

After waking in the morning

When you wake up each day, your body starts with a water deficit. Hydration is reduced through perspiration and condensation in your breath as you sleep, not to mention shortly after waking during that first trip to the bathroom. Drinking a full glass of water is one of the first things you should do each day, even before you eat breakfast or have your morning coffee. Neuroscientist and Stanford professor Dr. Andrew Huberman makes it a point to consume 16 to 32 ounces of water before eating or consuming caffeinated beverages.This may seem like a lot, but rehydrating after sleep helps you shake off fatigue and give your brain the water it needs to face the day.

Before and after meals

Regardless of which meal it is, it’s important to have some water before you eat. Doing so helps you in a couple of key ways. First of all, you’ll start your meal hydrated and therefore will be less likely to gulp down sugary beverages due to thirst. Additionally, if you’re trying to manage your portions, that pre-meal glass of water will help you feel fuller fast. Likewise, it’s good to have some water shortly after your meal in order to aid digestion, so save some room at the end of your meal!

When you’re experiencing daytime drowsiness

If it’s mid-afternoon and you’re having a hard time keeping your eyes open, there may be a simple fix that’s quicker than a nap (and less risky, too, if you’re a heavy sleeper). Afternoon fatigue is often a sign of mild dehydration in the long period between lunch and dinner. According to the UK’s National Health Service, water can help with afternoon tiredness.

Before bedtime

This is where things get tricky. If you’re feeling thirsty after dinner and before bedtime, you’ve already gotten off track with your water consumption for the day. If you’re still several cups away from your daily goal, don’t try to make up for it by going to bed with a full bladder! Drink only as much as you need to quench your thirst, and pledge to meet your water requirements before the next sunset.