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Brandon Luu, MD@BrandonLuuMD · Dec 16, 2025

Circadian rhythm dysfunction is highly prevalent in ADHD Up to ~75% of patients have delayed sleep and wake timing,…

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Summary

A new paper reveals that up to 75% of ADHD patients have circadian rhythm dysfunction with delayed sleep/wake cycles, and targeted interventions like bright light therapy and low-dose melatonin can advance sleep timing and reduce ADHD symptoms. Combined approaches show the largest effects, advancing circadian rhythms by approximately 2 hours in adults.

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  1. #1

    Circadian rhythm dysfunction is highly prevalent in ADHD Up to ~75% of patients have delayed sleep and wake timing, and shifting the clock earlier is linked to symptom improvement I just published a paper on what this means for treatment. Here’s what we found 🧵1/12

  2. #2

    The circadian system is fundamentally disrupted in many with ADHD: -73-78% of people with ADHD have delayed sleep/wake cycles -80% experience insomnia -Dim-light melatonin onset has been found to occur ~90 minutes later in adults with ADHD compared to controls /2

  3. #3

    Changes in biological markers corroborate this: cortisol rhythms are blunted and delayed and core clock genes (BMAL1/PER2) show attenuated rhythms. /3

  4. #4

    Melatonin patterns have also been found to be abnormal, with delayed onset, blunted peaks, and higher daytime levels /4

  5. #5

    Now lets talk about treatment: Bright light therapy (10,000 lux lamp for 2 weeks) in adults with ADHD: ↑ DLMO advanced by 31 minutes ↑ Mid-sleep time advanced by 57 minutes Phase advances correlated with ↓ ADHD symptoms, particularly hyperactive-impulsive subscores /5

  6. #6

    Low-dose melatonin (0.5 mg nightly) in adults with ADHD: ↑ DLMO advanced by 88 minutes ↓ ADHD symptoms reduced by 14% The key is timing, not dose. Taking melatonin 3h before DLMO (~5 hours before desired bedtime) drives phase advance /6

  7. #7

    In children with ADHD, 3-6 mg melatonin for 4 weeks: ↑ DLMO advanced by 44 minutes ↑ Total sleep time increased by 20 minutes (control group lost 14 minutes) Long-term follow-up: 71% had behavior improvements, 61% had mood improvements /7

  8. #8

    Combined melatonin and bright light produce the largest phase advance: approximately 2 hours in adults with ADHD and delayed sleep phase. This matches the magnitude of delay seen in most ADHD patients. /8

  9. #9

    A behavioral sleep intervention (2 sessions with psychologists/pediatricians teaching sleep strategies) in 244 children with ADHD showed significant improvements at 6 months in ADHD symptom severity, sleep quality, behavior, quality of life, and overall functioning. /9

  10. #10

    In a winter study, phase advance in circadian preference was the strongest predictor of ADHD symptom improvement across both subjective and objective measures. This may explain the high overlap between ADHD and seasonal affective disorder /10

  11. #11

    This isn't a cure for ADHD, it's an adjunctive approach. 1) many people with ADHD have circadian dysfunction 2) it's easily modifiable with behavioral strategies 3) improving circadian alignment is linked to improved symptoms in a meaningful subset of patients So why not try it? /11

  12. #12

    Overall, the high prevalence of circadian dysfunction in ADHD, the consistency of biological markers, and emerging evidence for circadian interventions support considering routine screening, circadian interventions, and most importantly, more rigorous research /12

  13. #13

    Here’s the link to the study: frontiersin.org/journals/psych… For more comprehensive protocols on how to shift your circadian rhythm, check out my newsletter on this here: brandonluumd.substack.com/p/circadian-rh…