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Why is delirium worse in the evening or at night?

Page last reviewed: July 2026

Delirium is usually worse in the late afternoon, evening and night. A clear morning does not mean it has gone.

Delirium comes and goes through the day. The same person can hold a reasonable conversation at eleven in the morning and not know where she is by eight in the evening.

This is a common reason delirium gets missed. If the doctor sees her during a good hour, everything looks fine.

Why evenings are worse

Nobody can fully explain it. Tiredness builds up through the day. The light goes, and with it many of the cues that show you where you are.

Wards get busy when staff change shifts and pass on information, then suddenly quiet. Visitors leave and familiar faces go home. Sleep is broken by noise, lights and routine health checks. Illness disturbs the body’s own day and night rhythm.

Probably all of these contribute. None of them alone explains it.

Is this delirium or sundowning?

You may hear staff or family call this sundowning. That word is usually used about dementia rather than delirium.

Sundowning usually describes a pattern of increased confusion or distress later in the day in someone with dementia. Delirium develops over hours or days and needs assessment for an underlying cause. A person with dementia can also develop delirium. Tell staff about any new change from their usual pattern.

If the evening confusion is new, do not let the word sundowning end the conversation. Say what has changed and ask: could it be delirium?

What helps

  • open the curtains in the morning
  • ask whether the lights over the bed can be dimmed at night
  • glasses on and hearing aids in during the day
  • visit in the late afternoon rather than at midday
  • keep a clock and a calendar in view

Tell the staff what the evenings are like. If they only see her in the morning, they are seeing the best hour of her day.

When to get help

Delirium (acute confusion) is a medical emergency. Outside a care setting, call local emergency services now. In a hospital, care home or nursing home, tell staff immediately. Say what has changed and ask whether it could be delirium.

Get help now: who to contact and what to say.

This page is general information, not advice about an individual. Written by Professor Alasdair MacLullich, Professor of Geriatric Medicine, University of Edinburgh. Reviewed July 2026.