The Half-Glass Volume Taper
Keep the same number of evening drinks but halve each one, so the habit survives and the fluid load does not.
- Difficulty
- Starter
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 89%
The input is a person who is very well hydrated, drinks a lot of liquid, and almost always gets up to urinate in the night. Walker starts by closing off the alternatives. There is nothing he knows of that helps suppress that reflex and desire during sleep; the few medications that exist work by increasing the expulsion of urine before bed so that less fluid is left as you cast off into sleep. Ferriss had already tested desmopressin, an anti-diuretic hormone, and ended up with orthostatic hypotension, standing up dizzy, and abandoned it as dangerous. And simply drinking less is advice Ferriss says he is very bad at following. So Walker's mechanism attacks volume while protecting the habit. Starting at 5pm or 4pm, he does not stop drinking the number of drinks he has; he just has half the size of the drink he normally would. He still has the same number of drinks, so his habit is still satisfied with having three or four, but the volume is halved. The stated reason is twofold: the psychology is still easier to adopt, and he does not fool his brain into thinking it is in a famine of fluid. The output is a 50 percent reduction in evening fluid load with no change to the ritual, which is what makes it stick. Ferriss agreed on air to try what he named the Dr Walker half glass trick.
Origin
Walker developed this on himself as he aged and began getting up at least once every second night, after finding no medication that suppresses the night-time urination reflex. He now advises it to people who raise the problem with him.
Core principles
- 01There is no medication that suppresses the urination reflex during sleep, so the lever is fluid timing and volume, not pharmacology.
- 02Existing drugs work by increasing expulsion of urine before bed rather than by blunting the night-time signal.
- 03Sleep continuity is a distinct outcome from sleep duration, and waking to urinate degrades subjective restfulness on subsequent mornings.
- 04Telling yourself to drink less fails because it attacks the habit, and the habit is what enforces compliance.
- 05Halving the volume while keeping the count intact preserves the ritual and fools the brain into not registering a famine of fluid.
- 06The intervention starts in the late afternoon, around 4pm or 5pm, not at bedtime.
How to run it
- 1
Rule out the pharmacological route first
Understand that no available medication suppresses the reflex during sleep. Existing options increase pre-bed urine expulsion rather than blunting the night-time signal, and anti-diuretics carry real risk.
Pro tip Knowing there is no drug answer removes the temptation to keep searching for one instead of changing behaviour.
Watch out Ferriss tested desmopressin and experienced orthostatic hypotension, standing up really dizzy, and judged it dangerous enough to stop; nobody should attempt it without medical supervision.
- 2
Count your current evening drinks
Establish how many drinks you actually have from late afternoon onward. That count is the thing you will protect, so you need the real number.
Pro tip Walker's own baseline is three or four drinks in that window, which is the count his habit is satisfied by.
Watch out Underestimating the count means you will unconsciously reduce it, which reintroduces the deprivation the method avoids.
- 3
Set the taper start at 4pm or 5pm
Begin halving volumes in the late afternoon and early evening, not at bedtime. The point is to reduce the total fluid load carried into the night.
Pro tip Starting earlier gives the load more time to clear before you cast off into sleep, which is the same principle the pre-bed expulsion drugs exploit.
Watch out Applying the taper only in the last hour before bed leaves most of the evening's fluid intake untouched.
- 4
Halve each drink, keep the count
Serve half the size you normally would while having the same number of drinks. The habit stays intact, the psychology stays easy, and the impact is reduced by 50 percent.
Pro tip Walker's stated reason for keeping the count is not fooling your brain into thinking you are in a famine of fluid.
Watch out Cutting the number of drinks instead of the size is the version that fails, because it attacks the habit that carries the compliance.
- 5
Measure by morning restfulness
Track whether you woke to urinate and how rested you feel the following morning, comparing tapered against untapered nights.
Pro tip Ferriss reports a marked difference in feelings of restfulness on subsequent mornings depending on whether he got up in the night, which is the signal worth tracking.
Watch out Judging by total hours in bed will hide the effect, because the variable being improved is continuity, not duration.
In the wild
Walker said he has definitely experienced this as he has got older; he used to sleep throughout the night and now gets up on average at least once every second night to go to the restroom. Having found no medication that suppresses the reflex, he worked out the half-volume, same-count approach for himself and now recommends it when people raise the problem.
→ The same number of drinks, half the volume, and roughly a 50 percent reduction in evening fluid load, arrived at by designing around the habit instead of against it.
Before this, Ferriss had tested desmopressin, an anti-diuretic hormone, which he stresses nobody should do without medical supervision. He ended up experiencing orthostatic hypotension, standing up and getting really dizzy, and concluded it was dangerous enough that he did not want to screw around with it.
→ The pharmacological route was closed off by side effects, leaving behaviour design as the only remaining lever and making the half-glass taper the practical answer.
Common mistakes
Cutting the number of drinks instead of the size
The whole design depends on keeping the count so the habit remains satisfied. Reducing the number attacks the ritual directly, which is the version of the advice Ferriss says he is very bad at following.
Reaching for an anti-diuretic
Walker knows of nothing that suppresses the reflex during sleep, and Ferriss's own trial of desmopressin produced orthostatic hypotension and dizziness on standing, which he judged dangerous enough to abandon.
Starting the taper at bedtime
Walker starts halving at 4pm or 5pm. Applying the change only in the final hour leaves the bulk of the evening's fluid intake unchanged and does not reduce the load carried into the night.
Is it for you?
Best for
Someone who drinks a lot of liquid, values the ritual of having several evening drinks, and notices a marked difference in restfulness on nights they do not get up.
Not ideal for
Anyone whose nocturia has a medical cause requiring diagnosis, or who is already fluid-restricted on medical advice.
From the transcript
“there's nothing that I know that helps suppress that reflex and that desire during sleep”
“starting at 5:00 p.m. or 4 PM I actually will just have half the size of the drink that I normally would so I don't…”
“I still have the same number of drinks so my habit is still satisfied with having three or four you know whatever drinks I'm having…”
“the psychology is still easier to adopt but the impact is reduced by 50%”
From the episode
#654: Dr. Matthew Walker, All Things Sleep Continued — The Hidden Dangers of Melatonin, Tools for Insomnia, Enhancing Learning and Sleep Spindles, The Upsides of Sleep Divorce, How Sleep Impacts Sex (and Vice Versa), Adventures in Lucid Dreaming, The One Clock to Rule Them All, The IP Addresses of Your Memories, and More