• Insomnia effects on daytime alertness (ICSD, DSM-IV). It also effects daytime behavior, quality of life (Léger, 1995) and has costly economic consequences. This economical impact of insomnia can be divided into direct and indirect costs.
• Direct costs of insomnia concern the direct economic consequences of insomnia in terms of outpatient visits, hospitalization, and sleeping medications.
• Indirect costs of insomnia include the potential consequences of insomnia, such as health problems, professional consequences and accidents. This is more controversial, as we don't know if sleep disorders are the cause or the consequence of various somatic or psychiatric diseases.

Several authors have evaluated the burden of insomnia on society. We have tried to summarize the work that has been accomplished in that field and to underline what could be undertaken to better understand social and economic consequences of insomnia.

Direct costs of insomnia include outpatient visits, sleep recordings and medications directly devoted to insomnia. There is very little knowledge about this kind of cost. Walsh et al estimated the direct costs of insomnia to be $10.9 billion in 1990 (with $1.1 billion devoted to substances used to promote sleep and $9.8 billion associated with nursing home care for elderly with sleep problems). The directs costs related to sleep disorders evaluation by practicianers, seem to be a small part of the total cost of insomnia. The Gallup study found that only 5% of insomniacs had ever specially visited a physician to discuss their sleeping problem. We found in a recent study on the impact of insomnia (Léger, 1997) that 53% of severe insomniacs and 27% of subjects with occasional sleep problems had ever visited a doctor specifically for insomnia (p < 10-4). During the past year, they were respectively 18% (16% a GP; 2% a specialist) vs 8% (7% a GP; 1% a specialist) (p < 10-4), with an average of 0.34 (+/- 1.56) visits by insomniacs and 0.1 (+/-0.50) in the other group (p = 0.0020).

Indirect costs of insomnia

Several studies have demonstrated insomnia effects on health, on professional life and on accidents. However several reports on the subject underlined the need for more information and studies (Roth, 1996)

We also found that insomniacs consumed more medication than good sleepers for various treatments , however there was no difference for analgesics despite the fact that 46% of insomniacs vs 29% of good sleepers (p < 10-4) said they were particularely sensitive to pain.

These results confirm previous observations showing that insomnia is statistically linked to a worse health status than individuals with good sleep. We cannot conclude whether insomnia is the cause or the result of this worse status. However, one could reasonably hypothesize that insomnia promotes fatigue which could increase the risk of some diseases or more simply decrease the threshold of others that could more easily develop. This hypothesis has been clearly demonstrated by Ford and Kamerow (1991), in a group of 705 people under 65 who had been followed for 3 years. The individuals who suffered from insomnia at the beginning were more than three times as likely as those without sleep problems to be depressed two years later. A similar result was observed for alcoholism in the same study. These observations have been confirmed by a another study by Livingston (1993) in a population of elderly subjects.

Insomnia can result in difficulties in coping with daily work, difficulties of concentration, work accidents, and difficulties in accomplishing work duties. Mendelson (1984) showed in a group of 691 non-treated insomniacs a clear loss of diurnal performance. Lavie (1981) found worse work satisfaction for insomniacs and a loss of productivity. Johnson (1983), in navy men, demonstrated than insomniacs were slower at work and had poorer career advancement than good-sleepers. Based on this last study, Stoller (1996) estimated the loss of productivity due to insomnia in the U.S. to be 41.1 billions US$ in 1988.