There are probably experts on this clinic who can offer more extensive responses to the subject of sleep, however I have a lot of experience in dealing with insomnia and sleep effected by FM - and the field of hypnosis does have an impressive evidence base for helping advance sleep.
On a generic note, studies such as that conducted by Parkes (1985) gives an average number of hours of sleep as 16 out of 24 for neonates, 8 for 12-year-olds, 7 for adults and 6 in old age.
However, people vary in the amount of sleep that they require, and duration of sleep may be influenced by habit so that, for example, people may find that they manage on less sleep after an imposed period of reduction in sleeping time, according to Home (1992) over several days, healthy adults may adapt without difficulty to up to 2 hours' less sleep.
Complainers of sleep-onset insomnia habitually overestimate the time they take to fall asleep (Franklin 1981). In a study by Stepanski et al (1988), the total monitored night-time sleep in patients complaining of insomnia was 364 minutes, compared with 419 minutes for people not complaining of insomnia. Therefore, many of the people complaining of insomnia may still have sufficient sleep. I realise that stating this can serve to get people's backs up; that is not my intention, promise!
Moreover, daytime EEG monitoring revealed that sleepiness in the complainers was no higher than in the non-complainers. However, complainers of insomnia usually report feeling drained and fatigued during me day, and rather than loss of sleep, this may involve anxiety and depression (which may include anxiety about not sleeping sufficiently).
Hence, insomniacs may underestimate the time they are asleep. (This is something that nurses on night shifts often notice with patients who complain that they are having little sleep.)
Nevertheless, it is possible that sleep quality is poorer in complainers of insomnia, with more periods of restlessness and troubled dreams. I think this is more relevant to your own query.
Whatever the case, psychological factors such as stress, anxiety and tension appear to be inextricably linked with complaints of poor sleep. According to Home (1992), psychological factors play some role in as many as 80% of all insomnia cases. I can only really comment on psychological factors and those within my own sphere of professional competence, I am no GP or physician.
For the benefit of others reading this, and I apologise that this is not wholly relevant to your own query, here is some general advice for those suffering with sleep disorders related to FM:
I realise that people who seek treatment for insomnia are usually well appraised of the rules and ploys for maximising the likelihood of a good night's sleep.
Obvious requirements are a comfortable bed and a dark, quiet environment that is neither cold nor overly stuffy.
Avoidance of any central nervous system stimulants in the hours before retiring is commonly advised, with tea and coffee particularly in mind. On the other hand, it is considered that = warm milky drink may be of benefit.
Alcohol may facilitate sleep onset but muse waking later in the night, so is not usually advised.
Poor sleepers sleep even more poorly if the period immediately prior to retiring is spent studying. Conversely, many people find that light reading or an easy-to-watch television programme is of assistance (see Home 1992, Parkes 1985).
A heavy meal, taken soon before retiring, or vigorous exercise, is not recommended. There is an idea, however, that regular exercise does promote good sleep. It may be the case that this is more to do with establishing a regular, healthy routine of work, rest, play and eating. Too restrictive a diet and hunger exacerbate insomnia.
If possible, times of retiring to bed and rising in the morning should be fixed, although lie-ins are fine at weekends and during holiday breaks. Daily naps are not precluded although it is better that these are taken at a fixed time of the day. Around 20 minutes should not pose a problem.
However, in the initial stages of treating insomnia, it is a good idea to prohibit napping until the sleeping pattern has been restored.
Many patients will be taking night-time sedation and may have done so for some considerable time, maybe months and even years. Nowadays, however, doctors are much more reluctant to allow repeat prescriptions of sleeping tablets, except perhaps in the elderly. Sleeping tablets can be helpful for short-term insomnia (up to 4 weeks). Thereafter, patients find that when they try to do without them, the insomnia returns, sometimes with a vengeance. It is difficult for many patients to go 'cold turkey', so a period of gradual withdrawal, in tandem with a psychological approach, is recommended. Some doctors consider that the withdrawal of medication may be facilitated by substituting the existing prescription with a longer-acting tranquilliser such as diazepam.
My own work tends to comprise of psychological treatments for insomnia:
Three main psychological approaches for alleviating insomnia have been investigated by well-conducted clinical trials that have incorporated plausible placebo controls. These approaches are stimulus control, paradoxical intention, and relaxation (including hypnosis). All appear equally effective, although relaxation methods may yield subjective ratings of more restful sleep (Espie et al 1989, Turner & Ascher 1979).
It is important to remember that all three methods involve the gradual breaking down of the habit of lying awake, and the re-installation of a regular sleeping pattern. This can only take place over a period of time. I know you stated that you relax before bed, but sustained and developed relaxation skills may be more beneficial (if you are not using them already, apologies if so).
The vast majority of psychological processes are designed to lull to sleep or to get to sleep, however, you have no issue with that.
Some self-hypnosis processes can also help with quality of sleep. If you bear with me for a day or so, I may be able to post another blog entry here on this site to offer up a simple step-by-step self-hypnosis process to help. Believing in your ability to sleep is also another method that has been shown to help. Having a positive expectancy about your ability to sleep aids the process, whereas trying to 'will yourself' to sleep for longer or more deeply or getting annoyed, frustrated or anxious about not sleeping for long enough often impairs our ability further.
I'll add a note here when I post the article on the blog which I hope will offer you something a lot more tangible.
Best wishes, Adam.