When the underlying cause of sleep problems is not immediately obvious, behavioral treatments are usually the first suggested. These range from patient education about sleep hygiene to cognitive behavioral therapy (CBT). Studies of both younger and older adults</ref> have compared CBT to medication and found that CBT should be considered a first-line and cost-effective intervention for chronic insomnia, not least because gains may be maintained at long-term follow-up. Sleep physicians and psychologists, at least in the US, are not in agreement about who should perform CBT nor whether sleep centers should be required to have psychologists on staff. In the UK the number of CBT-trained therapists is limited so CBT is not widely available on the NHS.