Use the two-process model to diagnose your specific sleep problem

Identify whether your sleep issue is a Process S problem, a Process C problem, or both — because the fixes are different.

Why it works

The two-process model makes sleep problems tractable by distinguishing their causes. Process S failures (can’t build enough pressure — common in sedentary, low-demand days, excessive napping, or spending too long in bed) require time-in-bed restriction and activity increase. Process C failures (clock is misaligned — common in shift work, social jetlag, irregular schedules) require timing interventions: light management and schedule anchoring. Treating a Process C problem as if it were a Process S problem (more pressure, more effort to sleep) typically makes it worse.

How to do it

1. Ask: "Can I fall asleep fine, but at the wrong time?" — that is primarily Process C.
2. Ask: "Does it take forever to fall asleep even when I am genuinely tired?" — that is likely Process S or arousal.
3. Ask: "Do I feel no sleepiness at my target bedtime?" — that may be a combined problem: low S and early C gate.

Evidence

The two-process model is the conceptual basis of modern sleep medicine and the guide for CBT-I protocol design; its diagnostic utility is well established in clinical sleep practice. (clinical)

Self-diagnosis of sleep problems has limits; if issues are severe, persistent, or involve significant daytime impairment, clinical assessment is warranted.

Sources

• Borbély (1982), a two process model of sleep regulation, Human Neurobiology

Common mistake

Treating all sleep problems the same — trying melatonin (a Process C lever) when the problem is Process S, or sleep restriction (a Process S lever) when the problem is a circadian misalignment.