Reading in bed

In sleep medicine books it is often said that reading in bed can disrupt sleep. Reading is good to relax before going into bed, but the bed should be reserved for sleeping.

http://www.nhlbi.nih.gov/health/public/sleep/healthy_sleep.pdf:

Chronic insomnia is often caused by one or more of the following: ...
Sleep-disrupting behavior such as ... or reading while in bed ...

Avidan et al (2006). Handbook of Sleep Medicine:

“Sleep hygiene rules: ... avoid reading in bed ...”

Colten et al (2006). Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem:

Stimulus control therapy: A set of instructions designed to reassociate the bed/bedroom with sleep and to reestablish a consistent sleep-wake schedule: Go to bed only when sleepy; get out of bed when unable to sleep; use the bed/bedroom for sleep only (e.g., no reading, watching TV); arise at the same time every morning; no napping.

So according to the experts after you have been in bed for 20 minutes without falling asleep, you should jump out of your bed into the cold and then (for example) read a book to relax. I didn’t even try it, how can I stay warm? Should I keep on the heating the whole night? Or take my eiderdown with me, but is that not also against Stimulus control therapy?
At least nobody seems to propose that laying in bed while keeping yourself awake with your own thoughts is the best option.

I consider reading till I fall asleep the best way to deal with insomnia. It keeps me less awake than distracting thoughts and it is less a waste of time.

It success depends on selecting the right reading material. The kinds of books most people associate with reading at night are the worst choice; don’t read exciting novels in bed.
The reading material should satisfy three partly conflicting criteria:
1. You should be able to concentrate on it;
2. You should want to read it;
3. It should be sleep-inducing.

Because my concentration ability can vary, I have different reading options lying beside my bed. As I can’t concentrate on a more difficult text, I turn to the easier one. If I concentrate well, but don’t fall asleep, I turn to a more difficult text.
The most critical part is turning the book away, turning the light off and now falling asleep. To keep sleepy I try to keep thinking about what I read in the book.