**5.5 Weight loss**

Upper-body obesity is a risk factor for OSA, and it is well documented that weight loss has a notable ameliorative impact on the occurrence of OSA (Ancoli-Israel et al., 1996; Smith et al., 1985). Since OSA results from closure of the airway, excess fatty tissue in theneck area may be a contributing factor. This supports the notion that weight plays a significant role in the presence and severity of sleep disordered breathing although no conclusive treatment trials have been published at this time.

### **5.6 Light therapy**

The most influential treatment for circadian rhythm disturbances is increased exposure to bright light. This form of therapy, which directly targets the circadian system, is much preferred over hypnotics and other sedative medications. Since light is the most important synchronizer in our circadian system, increasing bright light exposure during certain times of the day can shift circadian rhythm phase and increase its amplitude. Specifically, bright light exposure in the evening causes a phase delay, while morning bright light exposure causes a phase advance in circadian rhythms, including rhythms of melatonin, core body temperature and sleepiness (Martin et al., 2000).
