Circadian downshift failure explains insomnia

A 24‑hour circadian isolation study found that older adults with chronic insomnia do not shift their cognitive state from daytime problem‑solving to nighttime disengagement as strongly as good sleepers. The deficit appears intrinsic to the brain’s transition mechanisms (not just environment or behavior) and was measured hourly in a dim, time‑neutral setting. — If insomnia reflects a failure to disengage biologically, public health and clinical strategies should prioritize disorder‑specific circadian and neural interventions rather than one‑size‑fits‑all sleep hygiene advice.

Sources

Your Biological Clock is More Complex Than You Think

Jake Currie 2026.03.06 80% relevant

The article emphasizes that humans have a central clock plus peripheral clocks (liver, kidney, muscles, etc.) and that abrupt phase shifts (Daylight Saving Time) disrupt these systems—this concretely ties to the existing idea that failures in circadian downshifting produce sleep disturbance and downstream health harms.

Here’s Why Some Insomniacs Can’t Sleep

Bob Grant 2025.12.04 100% relevant

Sleep Medicine study of 32 older adults (16 insomniacs, 16 controls) monitored hourly in dim, time‑neutral beds and assessed cognitive‑state controllability and quality; insomniacs showed weaker downshifts.