With winter weather bearing down, in doctors' surgeries across the land, the sick note season is under way. But as people make appointments for their notes - technically known as "Med 3s" - the Health and Safety Executive (HSE) is intent on stamping out a large proportion of long-term sick leave. Each year in the UK, 166m days are taken as sick leave, and long-term sick leave - 20 days or more - makes up a third of this. But surely you need several weeks off work for ailments such as back pain, stress and depression?

The HSE thinks not. It has said, in new guidance published last week, that the culture of taking time off work for such complaints has to come to an end: "When you're off sick, returning to work as soon as possible may help you get well. And staying at home longer than you absolutely need to could actually make you worse."

This may seem an odd idea. Yet there is much in favour of the HSE's position. There is no doubt that a few days off - and people can sign themselves off for the first week of an illness without the need for a doctor's note - can be useful. A labourer who has severe lower-back pain may find, at first, that working is painful and taking a few days off work is helpful. But while 20 years ago, weeks of bed rest would have been recommended, now there is a swath of evidence proving that bed rest is one of the worst things you can do in a typical case of lower-back pain. Instead, keeping up and about is the fastest way to get better.

But surely it is best to take time off work because of stress? Much of the time, workplace stress is a cause rather than an effect of illness, as commentators from several unions have pointed out. If stress or depression is caused by difficulties at work, how can it be fair to expect people to go back, with a fear of relapse?

But as the HSE says, "The return to work is part of the recovery process and can safely happen before symptoms die down." For many people this is true: taking time off during depression may be necessary - concentration and memory, for example, may be impaired, affecting the ability to work. After a while, however, the loss of social contact, routine and the responsibility of employment may decrease confidence and self-esteem, quite apart from the financial implications of having to live on benefits. Indeed, as psychiatrist Professor Wessley says on the Department for Work and Pensions website: "Overall, work is good for mental health, and helping people to get back to work is probably the single most important thing that we can do for them."

Michael Summers, chairman of the Patients' Association, agrees. "There are some people who do take advantage of the system, but they are a minority. We generally encourage people to get back to work as soon as possible, and to ask their employers for lighter work if necessary."

In many ways, this is the bottom line. If employers can make accommodations for people returning to work, staff will be able to return sooner. This is not lost on the HSE, which makes many suggestions about how the workplace can support a person's return to work - for example, a part-time reintroduction to work, with a gradual increase in hours, or "buddy" mentoring. However, there are limitations. Large companies will usually be more flexible than smaller ones. And what happens when an employer is unwilling to make changes, or only minor changes are offered, and an employee still feels unable or unhappy to return to work?

All too often, the employee ends up stuck on long-term sick leave. And the truth is that when doctors fill in sick notes - or don't - conflict, obvious or latent, can be created. If a doctor recommends that a patient should return to work, it can cause offence, even anger, if the patient disagrees.

Doctors may avoid conflict by not challenging the request for a note. A study last year in the BMJ showed that many doctors were "disillusioned" with the current system and some simply acquiesce to the patient's request. And because many types of symptoms that lead to long-term sick leave are subjective, this can lead to further mistrust - on both sides.

The problem for doctors is that they are effectively being asked to police sick leave, ensuring that sick leave is genuine and that employees are returning to work promptly. But this should not be the role of the GP: family doctors should be allowed to act as the patient's advocate, not as a gatekeeper for the Benefits Agency. A doctor acting in the patient's best interests may still be advising a return to work. But the doctor's ambivalent position - between patient, employer and Benefits Agency - does not make it clear to the patient that the advice to go back to work is for his or her benefit alone.

Even if patient and doctor are agreed that a return to work is for the best, how can this be achieved if there are still problems at work? In an ideal world, occupational health departments would aid patients to return to work and guide employers into doing this. But these are not universally available. Some other schemes may help - the Back to Work scheme, for example, allows physiotherapists to work with patients in order to address specific problems and speed up the return to employment.

Sadly, the role of the occupational therapist is not mentioned in the HSE report. Sheelagh Richards, chief executive of the College of Occupational Therapists, is passionate about the role that OTs can play in helping people get back to work. "Human beings are 'occupational beings' - what we are is about what we do. In engaging in occupations, we give our lives meaning and satisfaction." However, underfunding of OT services in the 1980s means that OT has lost much of the capacity it once had. In addition, the emphasis on management of chronic disease in the community has not been accompanied by input of resources into primary-care OT services. Yet the objective and observational approach of occupational therapists could be the most practical help for patients returning to work. If I was able to refer to community occupational therapists more often, I might sign fewer sick notes. That would be good for everyone.

But in any case, the concept of the doctor's note is coming to an end. We are promised electronic medical records, which should make it easier for employees to certify themselves off on sick leave. And why not? Instead of using doctors as gatekeepers for the Department for Work and Pensions, why not let doctors try and help people to get back to work - except without any conflicts.