There are many different sorts of insomnia. Trouble falling asleep, trouble staying asleep and the one where you wake up around 5 am and can't go back to sleep until 6 or 6.30 or so and then get rudely awakened by your alarm after what seems only minutes later. Ever wondered what that one is all about? This is what.
Hailing back to primitive times when we went to sleep at dusk and rose at dawn our bodies natural hormonal cycle has been producing a bit of cortisol (one of the stress hormones) around 5 am to help you wake up and start your day. Hardly anybody's day starts at 5 am anymore, so how come some people sleep right through that natural wake up call and some people don't, regardless of when they went to bed? The culprit is the cortisol level you go to bed with. In other words: the people that are stressed when they go to bed not only have a harder time falling asleep, they also tend to wake up and stay awake at 5 when the extra bit of cortisol gets added to their already high levels. The reason they fall back asleep around 6 is because the body stops producing cortisol at that time. In the long run this form of insomnia can lead to sleep deprivation.
So how do you lower your cortisol levels before you go to bed to avoid this unwanted 5 am wake up call? You could try to get rid of the causes of your stress to avoid the hormones building up, of course. But if that is unpractical or illegal, at least make sure you stop working a few hours before bedtime. Do not try to wind down with TV, sugary foods or alcohol, those are related to other forms of insomnia. Your body will process and get rid of cortisol and other stress hormones best through exercise. Now, if you reintroduce stress by being fiercely competitive with the exercise you do in the evening, you're missing the point. Also: you don't want to exercise hard in the evening, because it will keep you from falling asleep by raising your body temperature. A stroll around the block will do, and of course, a gentle evening yoga practice would be ideal. String some of your favorite poses together with some breathing practice, a short meditation and end with a moment of gratitude. Give it a shot!