After a short night, the smallest follow-up is the hardest task

After a short night, I deliberately go for the small, easy things. And of all things, the items that mean following up with someone are the ones I find hardest on days like that. Yet none of them is much work. A clinical psychologist who works with GTD herself simply replied: “Now you know why.”

She was referring to a series of studies on what sleep deprivation does to people whose self-management actually works. Her conclusion: a good system organises your tasks, but it does not protect you from the biological effects of too little sleep. And you barely notice those effects in yourself.

The one criterion you have to estimate

In GTD, you decide what to do in any given moment by four criteria: context, time available, energy available and priority. You can read context and time straight off, and priority follows from your commitments and goals. Energy is the one you have to estimate, and you do it with precisely the brain that works worst after a short night.

Hans Van Dongen and colleagues showed just how badly in 2003, in the journal Sleep. For 14 days, healthy adults were allowed to spend either four, six or eight hours a night in bed, and time in bed is not the same as sleep. With four and six hours, their results in tests of attention and reaction time got worse day by day. The participants, by contrast, rated their sleepiness only slightly higher. The authors conclude that they were largely unaware of their growing deficits.

For choosing your next actions, this means: after a short night, the criterion meant to protect you from taking on too much is measured with an instrument that gives a false reading. And it errs on the comfortable side.

What slips after a short night

Concentration is only the best-known part. For working with lists, three other studies are more interesting.

What slips	Study	What it means for your lists
Performance and self-assessment	Van Dongen and colleagues, Sleep, 2003	Mistakes in figures and facts that you don’t notice
Regulating emotions	Li and colleagues, Nature and Science of Sleep, 2023	With delicate replies, your first reading wins
Closeness to others	Ben Simon and Walker, Nature Communications, 2018	Following up, phoning and checking back become hard
Willingness to help	Ben Simon and colleagues, PLOS Biology, 2022	Other people’s requests are more likely to be left undone

When you are well rested, you can check your first interpretation of a situation before you react. For example, whether a client’s sharp email might have a more innocent explanation. Psychology calls this cognitive reappraisal. In 2023, in a randomised study with 39 participants, Li and colleagues found signs that this is exactly what works less well after sleep deprivation. Not every study finds this effect, but the direction is still enough for a practical rule.

In 2018, Eti Ben Simon and Matthew Walker of the University of California, Berkeley, studied eighteen young adults, once after a normal night’s sleep and once after a night spent awake. When overtired, they wanted to keep more distance from other people. Outside observers watched videos of them and rated the overtired participants as lonelier and less socially attractive. The withdrawal runs both ways.

Four years later, the same research group looked at willingness to help: in the lab, in everyday life and in more than three million donations in the US around the switch to daylight saving time. All three approaches point the same way. Anyone who sleeps less helps less, and after the clocks went forward, people gave less.

The psychologist sums it up like this: “A GTD system can make tasks visible and organise them sensibly. But it does not change our willingness, in the moment, to give some of our energy to others.” That also explains why I find the follow-ups hard. They are small, but they demand exactly what is missing after a short night: reaching out to someone.

Sleep deprivation and productivity: sort by type of task

Small and easy first is the right call after a short night. It’s just that on a day like that, easy means something different from usual. A reply to an angry email is small and still risky. Two hours of filing receipts is a lot of work and still perfectly safe. If you sort by size, you are sorting by the wrong thing.

Type of task	Examples	After a short night
Mechanical	filing, scanning, routine admin	well suited
Precision	figures, quotes, contracts, fact-checking	postpone or have someone check it
Delicate communication	reply to a complaint, critical feedback	write as a draft, send tomorrow
Reaching out to others	following up, asking for something, a quick call	make it small and get it done

The psychologist advises double- and triple-checking facts and important breakdowns on days like that. There is a catch: the second check is done by the same overtired brain that missed the mistake the first time, and it feels perfectly fit while doing so. If you can, move work with figures to tomorrow or have someone else check it.

Delicate replies clash with the two-minute rule. A reply to a complaint is quick to write, so it gets dealt with on the spot while you are processing. After a short night, that is exactly the mistake. Write it, save it as a draft and send it tomorrow, once you have read it through again.

With follow-ups, postponing does not help much. A follow-up does not get easier by being left; it only gets later. Make the step so small that it takes hardly any willpower: one sentence by email instead of a phone call, a message already worded so that all you have to do is send it. If you really can’t face it, give the entry on your Waiting For list a new date on purpose instead of letting it quietly go stale. And if on a day like that you would rather fob off a request for help, that may be down to your night rather than to the request.

This sorting is most reliable when you don’t do it the morning after at all. The energy question belongs to clarifying, not to doing. If, while processing, you note right away what kind of brain a next action needs, you answer the question once and with some distance. Otherwise it comes up again every morning, with whatever brain you happen to have that day. My context lists have long been sorted by energy instead of by place, and after a short night that pays off: the decision has already been made.

What the system does at night, and what it doesn’t

A complete system takes one kind of night-time thought off your mind: open loops. Marie describes how GTD has made her mental merry-go-round much smaller. Anything that has a next action and is written down is something your head no longer has to hold on to. Whatever still surfaces at night goes on a slip of paper next to the bed. For the tension that is left after that, Marie puts one hand on her chest and one on her belly. Then she breathes in for a count of six and out for a count of nine.

Paul Martin is familiar with brooding over problems “that even the best GTD can’t solve”, as he puts it. He has his own remedy for that, contrary to the usual advice not to look at a screen at night: woodworking videos in which someone explains, entirely unhurried, how to saw a joint between two pieces of wood. After a few minutes he turns it off, whatever was on his mind before has been pushed aside, and he can fall asleep again.

The two-process model explains why getting back to sleep is often harder than falling asleep in the first place. The sleep researcher Alexander Borbély presented it in the early 1980s. Sleep pressure builds up while you are awake and drains away again while you sleep; independently of that, your internal clock has its own say. Wake up an hour or two after falling asleep, and you have already worked off part of that pressure. Add tension, hyperarousal in the jargon, and you are dead tired and wide awake at the same time. If that keeps happening, the body comes to associate the bed with lying awake and frustration.

The German S3 guideline on insomnia in adults, last updated in April 2025, recommends cognitive behavioural therapy for insomnia as the first-line treatment. One of its components is stimulus control, and at first it feels wrong. If you can’t sleep, you get up, go into another room, turn the lights right down and do something calm. You only go back to bed once the tiredness has returned.

What you do during that time is what counts, and the criterion is: no suspense. A book that grips you will keep you reading until morning. For me, it was once an hours-long sleep story about a train journey, told so slowly that every falling leaf gets a mention. Every single time, I found it so suspenseful that I had to hear the ending. The psychologist recommends stories whose ending you already know. For me, that is the GTD audiobook, which I know almost by heart in both German and English. It can’t surprise me any more, which is why I often fall asleep to it.

If you sleep badly over a longer period, have it checked by a doctor. Sleep problems can have physical causes, such as sleep apnoea, and no list will solve those.

Where it typically fails

• Tiredness gets read as a motivation problem. If you feel listless after a short night, it is tempting to look for the fault in your system and rebuild your lists. On a day like that, the first question is about sleep.
• The second check is done by the same brain. Double-checking is reassuring, but it catches less than it promises. Work with figures belongs on a well-rested day or with someone else.
• The two-minute rule hits the wrong email. Replying straight away is normally a strength. With anything that annoys you, it becomes a risk after a short night.
• Follow-ups get quietly postponed. Your gut says tomorrow, and the next day it says tomorrow again. A date set on purpose is a decision; an entry left to gather dust is not.
• The night turns into a performance test. If you go to bed already telling yourself it won’t work anyway, you build up exactly the pressure that keeps you awake. That is why Marie pays deliberate attention to how she talks about it, including to herself.

Common questions

How does sleep deprivation affect productivity?

Sleep deprivation reduces performance without the people affected reliably noticing. In one study, healthy adults were allowed only four or six hours in bed per night for 14 days. Their test results got worse day by day, while they rated their sleepiness only slightly higher. There are also indications that after little sleep, emotion regulation and willingness to help suffer, and people seek more distance from others.

Can you tell for yourself how much sleep deprivation lowers your performance?

Usually not. With repeated short nights, the feeling of sleepiness rises only slightly, while measured performance drops considerably. After a short night, your own assessment is therefore a poor yardstick for which tasks you feel up to.

Which tasks should you postpone after a sleepless night?

Above all, postpone tasks that demand precision or tact, such as figures, contracts, quotes and replies to delicate messages. Delicate replies can be written as a draft and sent the next day after rereading them. Mechanical work such as filing or routine admin, on the other hand, is well suited to days like that.

What helps if you wake up at night and can’t get back to sleep?

Getting up helps more than lying awake in bed. That is the core of stimulus control. It is a component of cognitive behavioural therapy for insomnia, which the German S3 guideline recommends as the first-line treatment. You go into another room, do something calm and free of suspense in dim light, and only return to bed when the tiredness comes back.

Does GTD help you fall asleep?

Partly. GTD takes the open loops off your mind, because everything with a next action is safely written down and does not have to be held in your head. Even a complete system does not help with brooding over things that have no possible next action, or with the biological effects of sleep deprivation.

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After your next short night, take five minutes before you start on the first task. Go through your lists and mark everything that demands precision or tact as work for tomorrow. From what is left, you are free to choose by feel. But one follow-up still goes out today.

Whether your lists hold up on a bad day is decided when they are set up. If the energy question is built into the system, you don’t have to answer it in your head again every morning. In the Workflow Setup we build your lists so that they make that decision in advance. Write to me if, after short nights, you stand in front of your list and can’t tell what on it you can manage today.