Map the daylight across a reading room

Begin with a plan showing the window, the chair and any nearby wall or large piece of furniture. A quick sketch is enough. Mark where direct sunlight reaches at three times when someone might actually use the room. In a west-facing room, useful visits might be late morning, the start of the afternoon and an hour before sunset. Include the time beside each outline.

Use a symbol for the part of the room that is bright without a crisp shadow. A chair beside a shaded window can receive plenty of diffuse light, even while direct sun falls somewhere nobody sits. If the window faces a light-coloured wall, note that surface in the sketch. It may contribute more useful reading light than the patch of sun on your floor.

Put the chair in its normal position and set a book at the height you usually hold it. Try a second spot with the chair turned partly across the window. Keep the book angle, your reading distance and the page roughly the same on both trials. This lets you compare the effect of direction while the rest of the setup feels familiar.

A glossy page can reflect an image of the bright sky or window frame. Tilt a magazine slowly while watching a short line of print. If the words disappear at your resting angle and return when you turn the page, a small change in chair direction might solve the problem. Make the same check with matte paper. It will often be easier to read under a light that still produces distracting reflections on a magazine.

A sharp shadow across the upper half of a page can make very small type feel harder to read. Check whether the shadow comes from your hand, the edge of the chair, your body or a nearby curtain. Moving the chair sideways can change the edge of the shadow without making the whole room darker. Mark where your head and book were, since a standing observation can miss that relationship completely.

Repeat the preferred arrangement near dusk. Use the lamp you already have and check the same book. A shade that appears modest from the door can put a bright point in view once you lean back. Move the lamp rearward or farther to one side and see whether the page stays evenly lit. Leave enough room to return a book to the table without reaching across the lamp or its cable.

Under an overcast sky, map the same room using the same three positions. Skip the outline of direct sun if there is none and record which seats still support comfortable reading. The chair with the strongest sunny-day light may lose most of it under cloud. An alternative near a larger exposed part of the window may perform more consistently if it can be reached without blocking the room.

Choose a position you can live with and leave the room in normal use for a few evenings. Push the curtains back as far as people usually do, leave the side table in place and try the arrangement while someone takes the usual route through the room. Record the position and angle that worked, plus the time when you preferred the lamp. Keep that small map so you can test the same arrangement when the season or the furniture changes.

If the chair has two useful positions, mark both on the sketch. A small change between seasons may be easier than finding one arrangement that serves every time of day. Include where the lamp and side table go in each drawing.