Phototherapy and chronotherapy — consultant viva

Station structure

Time: 8–10 minutes. Depth: consultant teaching registrar. Expect named trials, lux/timing numbers, bipolar deltas, and stop rules without inventing local subsidy codes as universal law.[3]

Core questions and model points

1. What is phototherapy vs chronotherapy? Phototherapy is prescribed bright light exposure; chronotherapy is the class including light, wake therapy, sleep phase advance, dark therapy, and timed melatonin for rhythm and mood disorders.[3][8]

2. Default BLT prescription? About 10,000 lux, UV-filtered box, ~30 minutes shortly after waking, eyes open toward the device — not late evening.[2][3]

3. Why morning? Phase-response curve: morning light advances; evening light delays; morning often superior for winter depression; phase-delay models of winter depression support advance strategies.[3][5]

4. Can-SAD message? Light comparable to fluoxetine 20 mg oral daily in winter SAD; light may work faster early on.[4]

5. Nonseasonal? Lam 2016: morning light mono and light+fluoxetine superior to sham–placebo on MADRS.[6]

6. Bipolar rules? Prefer midday bright light titration under mood stabiliser cover (Sit); monitor switch; do not copy unipolar aggressive unsupervised morning megadoses uncritically.[7]

7. Wake therapy? Rapid antidepressant effect possible within a day; high relapse after sleep unless combined package; specialist supervision for high-risk patients.[8]

8. Eastman nuance? Specific light effect vs placebo may take about three weeks to declare in that winter trial — temper overnight-cure claims.[1]

9. Day-5 hypomania card? Stop/reduce light, reassess bipolar spectrum, stabilise, risk manage — light-induced switch is a hard stop.[3][7]

Pass / border / fail

• Pass: Correct lux/timing, Can-SAD and Lam names, bipolar midday logic, safety stops.[3][4][6][7]
• Border: Knows light for SAD but vague on parameters or nonseasonal evidence.[2][6]
• Fail: Evening bright light as default; ignores mania/ocular risk; light as sole care for severe SI/psychosis.[3][7]