If I could give one free sleep tip, it would be this: get bright light early and keep it dim late.

Why light matters

Your body clock reads light to work out what time it is. Bright light says "day". Darkness lets your body release melatonin, the hormone that signals night. Bright light in the evening can delay that signal.

Mornings: go outside

Indoor light is much weaker than daylight, even on a grey Swedish morning. Ten to twenty minutes outside soon after waking is a good start. In winter, I take my morning walk as soon as it gets light.

Daytime: get more of it

Take calls on a walk. Eat lunch by a window or outside. The contrast between bright days and dark evenings helps your rhythm.

Evenings: lights low and warm

• Switch off the big overhead lights after dinner.
• Use lamps or candles.
• Turn your phone's brightness down and use night mode.
• Try leaving the phone outside the bedroom.

Nights: make it properly dark

Small LEDs and street light add up. Blackout curtains or a sleep mask are cheap and effective.

Pair it with a calm routine

Light habits work best alongside a regular bedtime. If you use a supplement, keep it part of that routine. Tranquil contains magnesium, which contributes to normal functioning of the nervous system.

One change for this week

Get outside in the morning every day for seven days and notice how your evenings feel.

Food supplements should not replace a varied, balanced diet and a healthy lifestyle.