Hydration advice usually stops at a number: drink this many litres a day. But your body doesn't experience water as a daily total — it experiences it hour by hour. Drink most of it late and you trade a tidy daily figure for a fragmented night: more trips to the bathroom, more brief wakings, a softer recovery score. The fix isn't to drink less. It's to drink the same amount, earlier.
Two people can drink the exact same amount of water and sleep very differently, because the body doesn't average intake over 24 hours — it processes it as it arrives. A litre poured in over the evening leaves your kidneys working through the night; the same litre spread across the morning and afternoon is long gone by bedtime. So "am I drinking enough?" is only half the question. The other half is "when?" — and for sleep, that half does most of the work.
You wake up mildly dehydrated — a night of breathing and sweating with nothing going in. That makes the morning the natural time to drink the most: it tops you up when you're lowest and gives your body the whole active day to use and clear the fluid. Carry that habit through midday and the early afternoon, and by evening you've already met most of your target without thinking about it. Front-loading isn't a trick to drink less before bed; it's simply putting the water where your body can use it and clear it in daylight.
In the last couple of hours before sleep, a large drink has nowhere good to go. Lie down and fluid that pooled in your legs returns to circulation, your kidneys keep filtering, and a full bladder either wakes you (nocturia) or lightens your sleep without fully rousing you — either way the night gets choppier. The common-sense move is to taper: ease off fluids roughly two hours before bed, take only small sips if you're thirsty, and get the bulk in earlier. This is general guidance, not medical advice — frequent night waking to urinate, or a sudden change in thirst, is worth raising with a clinician rather than solving with timing alone.
A useful daily target for drinking water is about 27 ml per kilogram of bodyweight — roughly 2.2 litres for an 80 kg person — with more on hot days and hard-training days. Note that's drinking water specifically, not total water: the older 35 ml/kg figure counts everything, and food plus the water your body makes from metabolism cover the rest. Treat it as a baseline to aim near, not a quota to force down. The goal is to spread that amount sensibly across the day, with the tap easing off as bedtime approaches.
Vitra's Hydration page turns all of this into something you can just follow. From your bodyweight it sets a daily drinking-water target (around 27 ml per kg, nudged up for heat and activity) and paces it through the day — front-loaded earlier, then easing the target off in the roughly two hours before bed so you're not chasing water late. A drag-to-log bar lets you add what you drink in litres, millilitres or cups; a curve plots your target against what you've actually had, so you can see whether you're ahead or behind at a glance. History and daily totals build the bigger picture, and optional gentle reminders nudge you through the day and stop before bedtime. It's all computed on your own machine from your Oura data; nothing leaves your device.
Local AI on your Mac or PC. One-time purchase, 7-day trial, no subscription.
Download Vitra →