What the research describes about sleep

Sleep runs on the same two systems as daytime alertness: pressure that builds while you're awake, and a body clock that decides when sleep is available.

In otherwise healthy adults, the research describes most ongoing sleep trouble as those two being out of sync, not an inability to sleep.

Why does every plan fix your wake time?

A bedtime is an intention. A wake time is an event. Your body clock sets itself by the light after you wake, so a steady wake time sends a steady signal and a steady bedtime doesn't.

Clinical sleep restriction programs fix the wake time and let bedtime move. They report better results than fixing both.

Why get out of bed when you can't sleep?

Cognitive behavioural therapy for insomnia has the strongest evidence of anything in this area. One part of it is stimulus control.

The idea: lying awake in bed for long stretches teaches your brain that bed means awake. So the programs say to get up after a while instead of waiting it out.

Does tracking your sleep help?

Consumer trackers agree moderately with lab sleep studies on total sleep time, and poorly on sleep stages.

Clinicians also describe people getting anxious about their tracker data, which makes the sleep worse. That's why several programs drop tracking at the start.

Why is alcohol a special case?

Alcohol helps you fall asleep faster, then degrades the second half of the night: less REM early, more broken sleep later.

It's the clearest case in this field of something that improves the sleep you notice and worsens the sleep you don't.

When should you get checked?

Loud snoring, someone seeing you stop breathing, or deep daytime sleepiness despite enough time in bed are the described signs of sleep apnoea. It's common, underdiagnosed and treatable.

No schedule change fixes it, and the research is clear that it needs a proper check.