Does spending more time outdoors in bright sunlight (not really exercising) during the day decrease insomnia at night?

May help. Spending more time outdoors in bright sunlight during the day may help set your biological clock, and may help you sleep better. Exercising during the day is also helpful as long as it's not too close to your bedtime. Don't take naps. Get up and go to bed the same time every day. Avoid caffeine, nicotine and alcohol especially within 6 hours before bed. Take a hot bath before bedtime.
Outside. Great way to decrease depression, decrease insomnia, improve vitamin uptake from the sun--even on a cloudy day.