Why Evening Light Wrecks the Next Morning

You are tired at 8 PM and wide awake at 11. Before you blame your hormones entirely, look at your lamps.

What the researchers actually did

Gooley and colleagues kept participants in either dim light or ordinary room light in the hours before bedtime and measured melatonin onset, duration, and suppression under controlled laboratory conditions.

What they found

• Room-level light — not just screens — suppressed melatonin substantially.
• Melatonin onset shifted later, shortening the biological night.
• The effect appeared at light levels most people consider normal for an evening at home.
• A later melatonin onset drags the next morning's cortisol rise later too.

What it means for you

The menopause transition already fragments sleep. Layering a delayed body clock on top of it is what turns a hard night into a hard month. This is one of the few things you can change tonight without buying anything.

What to do with it this week

• After dinner, kill the overheads and use two lamps instead.
• Move the brightest light in the house to the morning, the dimmest to the evening.
• Warm bulbs in the bedroom and bathroom — the bathroom is the one everyone forgets.
• If you read on a screen, drop its brightness to the lowest setting you can still see.