The method

Multi-activity interval switching, explained

The focus method behind Sunny, in plain language: what it is, why it works when Pomodoro feels rigid and Flowtime feels shapeless, and how to run your first session.

Definition

Multi-activity interval switching is a focus method where you cycle between two or more activities you chose, switching at intervals you control, instead of alternating work with an idle break. Each activity has its own rule: a timed interval, or “until done”. The switch acts as a mental reset, so the “break” can itself be a productive activity.

Why work → rest breaks down

Nearly every focus technique models the same loop: work, then rest. Pomodoro fixes the rhythm at 25/5; Flowtime lets the work stretch until you tire and then prescribes a proportional break. Both treat the pause as empty recovery time.

Two problems show up in practice. First, a hard timer that interrupts you mid-flow is jarring, and it is the top complaint people have about rigid Pomodoro. Second, idle breaks leak: five minutes of “rest” becomes twenty of scrolling, and restarting costs more will-power than continuing would have.

The insight behind interval switching is that you don’t need to stop to recover, you need to change. Switching to a different activity resets attention almost as well as a break does, while keeping momentum. Discipline-heavy work starts to feel lighter, almost like a game: the next activity is something to look forward to, not a pause to endure.

Two ways to pair activities

The pairing is where you tune the intensity to your day:

Goal ↔ Leisure. Alternate a goal activity (writing, planning, a review pass) with something genuinely fun (a game, an episode). Lower intensity, for tired or low-motivation days. The leisure block is a real reward on a timer, not a guilty escape.
Goal ↔ Goal. Alternate two productive activities: a report and your inbox, two projects, writing and code review. Higher effort, remarkable throughput on strong days, because you’re always resting from one thing by doing another.

Two interval rules, mixed freely

Timed. Work a set duration, then switch. The classic advice is to treat the timer as god: the bell rings, you move, no negotiation. A softer variant sets the time as a minimum: push a little past the floor until you hit friction, then switch. Sunny supports both; in overtime the timer simply counts up past the chime until you move.
Until done. No countdown, nothing counted. The activity is a task you defined (“clear today’s inbox”, “finish one section”) and you switch when it’s done. This is essentially Flowtime applied to alternation. The quantity lives in your head; write it as a note if you like.

Crucially, the rules are per activity and asymmetric intervals are normal: 7 minutes of email against 25 of deep work, a timed block against an open-ended one. Adjusting mid-session, adding a few minutes here or converting a countdown to until-done there, is expected, not cheating.

Compared with Pomodoro and Flowtime

Comparison of Pomodoro, Flowtime and multi-activity interval switching
	Pomodoro	Flowtime	Interval switching (Sunny)
The loop	Work → idle break	Work until tired → proportional break	Activity A ↔ activity B (↔ C…)
The “break”	Rest, fixed length	Rest, proportional	Another activity, leisure or a second goal
Interval rule	Fixed (25/5)	Open-ended	Per activity: timed, minimum, or until-done; asymmetric is fine
Best when	You need external structure	Flow matters more than rhythm	Long sessions of repetitive or discipline-heavy work

The camps aren’t enemies: a timed rule is Pomodoro, an until-done rule is Flowtime. Interval switching spans both, which is why Sunny works as a plain Pomodoro or Flowtime timer too, if that’s all you want.

What fits, and what doesn’t

The method shines with bounded, well-defined activities: clearing an inbox, a set number of pages, one section of a report, a review pass, a practice drill. You can put them down and pick them up without losing much.

Deep-context work, like programming or writing that holds a big structure in your head, is a poor fit for frequent switching, because rebuilding context after each switch is expensive. Use longer intervals, an until-done rule, or a plain single-activity session for that kind of work. Sunny will gently point this out, never forbid it.

How to start

Start rigid. Pick two activities, give both a timed rule, and obey the chime for a few sessions. Structure first; looseness comes with experience.
Pair hard with easy on a normal day. Reach for goal ↔ goal when you feel strong.
Let the intervals be uneven. If five minutes of admin earns twenty-five of deep work, that’s the ratio. Tune it mid-session.
Graduate to until-done where quantities are natural (“one inbox sweep”, “one section”) and keep the timer where they aren’t.

In Sunny, the presets do step one for you: Classic 25/5, Short Cycles 10/3 and Study ↔ Play each start a correctly shaped session in one tap. You rename and retune once you know your rhythm.

Method questions

What is multi-activity interval switching?

Multi-activity interval switching is a focus method where you cycle between chosen activities at intervals. For example: deep work for 25 minutes, then email for 10, then back. The switch itself acts as a mental reset, so the “break” can be a second productive activity. Read the full write-up on the method page.

How is Sunny different from a Pomodoro app?

Pomodoro apps model work followed by an idle break, with one fixed rhythm. In Sunny, both sides of the loop are real activities of your choice, each side can have a different rule (25 minutes here, until-done there, 7 minutes somewhere else), and you can adjust mid-session. If you want plain Pomodoro, Sunny does that too: the Classic 25/5 preset is one tap.

Does Sunny support Flowtime?

Yes. Sunny's 'until done' rule is Flowtime applied to alternation: no countdown, no counting. Work until you finish what you intended, then tap Switch. You can mix rules freely, for example a timed activity on one side and an until-done activity on the other.

What activities work best with the method?

Bounded, well-defined activities fit best: clearing an inbox, a set number of pages, one section of a report, a review pass, a practice drill. Deep-context work like programming tends to fit less well at short intervals, because rebuilding context after each switch is expensive; give it longer intervals or an until-done rule. Two activities is the sweet spot to start, and Sunny supports three or more once you know your rhythm.

Is Sunny useful for ADHD?

Many people with ADHD find alternation easier than forced idle breaks, because novelty is built into the loop: the next activity is a reward rather than a pause. Sunny also avoids guilt mechanics. Streaks are positive-only, there are no shame notifications, and reminders are gentle and opt-in. That said, Sunny is a timer, not a medical tool.

Try a session, not a system

One preset, two activities, under a minute to start. See if the switch feels like rest.

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