Your energy through the day
Your alertness rises and falls on a daily curve, and your curve may not match anyone else's. Learn to find your best hours and put the right kind of work in them.
THE DAILY CURVE
Alertness has a shape
Your body clock (your circadian rhythm) raises and lowers alertness over roughly 24 hours. For many people the shape is similar: slow for a while after waking, a rise to a peak some hours later, a dip in the early afternoon, and some recovery in the late afternoon or early evening.
Someone who wakes at 7 might feel foggy until 8, sharpest from about 9:30 to noon, heavy around 2 or 3, and livelier again around 5. The exact hours differ from person to person.
Chronotype
Your natural timing: whether your body clock runs earlier (a "lark") or later (an "owl"). Most people are somewhere in between. Chronotype is partly inherited and changes with age: teenagers and young adults tend to run later, and people usually shift earlier as they get older.
Two flatmates keep the same schedule. One is sharp at 8am and fading by 9pm; the other is useless before 10am and doing her best thinking at 6pm. Neither is doing it wrong.
Check yourself
Parisa is a university student and clearly an owl. She read that successful people work early, so she sits down to write her thesis at 7am and mostly stares at the screen. She's sharpest from about 11am to 2pm. What should she do?
- Keep going at 7am; enough discipline will fix it
- Drink a strong coffee at 7am and push through anyway
- Move thesis writing to her 11-to-2 window
- Write only on weekends, when she can sleep in
Show the answer
Move thesis writing to her 11-to-2 window
Yes. Her best hours are the scarce resource, and the thesis is her hardest work. Other people's routines are built on other people's curves.
Two kinds of hours, two kinds of work
Peak hours
Work that needs deep thought: writing, solving problems, learning something new, planning a project, making a hard decision.
Low hours
Work that runs on routine: email and messages, forms and admin, tidying files, errands, meetings that are mostly updates.
Check yourself
Where does each task fit best?
- Writing the key section of a report
- Answering routine emails
- Learning a new chapter of physics
- Filling in an expense form
- Planning the structure of a presentation
- Sorting your downloads folder
Show the answer
Peak hours: Writing the key section of a report, Learning a new chapter of physics, Planning the structure of a presentation
Low hours: Answering routine emails, Filling in an expense form, Sorting your downloads folder
Find your curve in one week
- Rate yourself every two hours
On paper or in a phone note, score your focus from 1 to 5. It takes ten seconds.
- Note what might explain it
How you slept, when you ate, when you had tea or coffee. A bad night drags the whole day down.
- Look for the pattern
After five to seven days, find the two or three hours that are usually highest, and the stretch that's usually lowest.
- Protect the best window
Keep it for your most important task. In a later lesson you'll block it out in your calendar.
Check yourself
Babak tracked his energy and is sharpest from 9 to 11:30. He spends that time clearing his inbox "so his head is free," and starts his real project at 2pm. That's a good use of his peak.
Show the answer
False
False. Clearing email feels productive, but it's routine work that goes fine in a low hour. By 2pm he's in his dip, doing his hardest work with the least energy. Swapping the two gives the project his best hours.
THE CEILING
Sleep sets the height of the curve
Your curve assumes a reasonable night. After a short night the whole curve drops: even your peak is lower, and you get more lapses, those moments when your attention just blanks. Irregular wake times also shift the curve around. No schedule trick replaces sleep; a later lesson covers it properly.
After five hours of sleep, your "best hour" might feel like a normal afternoon. On days like that, do the one key task first and keep it smaller.
Check yourself
Match each moment to the best use of it
Show the answer
- Your sharpest two hours → Your most important thinking task
- The early-afternoon slump → Routine tasks or a short walk
- A second wind in the late afternoon → A shorter second round of focused work
- A day after a very short night → The one key task first, cut down in size
Check yourself
- Tom does a statistics problem set at 10am, his usual peak. It takes about an hour and he makes few mistakes.
- Tom does a problem set of the same kind at 3pm. It takes nearly two hours and he makes more mistakes.
Same kind of problems, same person, same week. What most likely made the difference?
- How hard that particular set happened to be
- The time of day
- How much statistics he knew
Show the answer
The time of day
Right. Nothing about the work or his knowledge changed. At 3pm he was working in his low hours, so the same thinking cost more time and more errors.
Lesson recap
- Alertness follows a daily curve: often a morning or midday peak, an early-afternoon dip and some recovery later.
- Your chronotype shifts that curve earlier or later; most people are in between, and it changes with age.
- Put deep-thinking work in your peak hours and routine work in your low ones.
- Track your focus for a week to find your curve, and remember that sleep sets its height.