Chapter 02
The sleep inversion
Melatonin can peak around midday. This is one of the most distinctive findings in the condition.
In most people melatonin rises in the evening, peaks in the middle of the night, and clears by morning. In SMS the curve is inverted: it rises in the morning, peaks around midday, and falls in the evening.
| Melatonin | Typical | SMS |
|---|---|---|
| Onset | ~9 PM | ~6 AM |
| Peak | ~3:30 AM | 12 noon |
| Offset | ~6 AM | ~8 PM |
This is not a sleep habit and it is not a parenting outcome. The pineal gland is secreting melatonin during the day and suppressing it at night — a complete phase reversal, tied to RAI1's role in regulating circadian clock genes. No bedtime routine addresses it, which is why families who have tried everything are not failing at something.
It is also a useful recognition cue. Developmental delay and behavioral difficulty are shared with many conditions; a documented inverted melatonin rhythm is much more specific.