Studies have shown that we generally sleep less than we used to in the past: time that was once spent asleep is now used for work or leisure, surfing the Internet, watching TV, etc.
A number of factors may also unsettle your sleeping patterns:
> Stress and anxiety are increasingly big factors. They increase secretion of cortisol (the stress hormone) and keep you awake.
> Hyperactivity leads to the build-up of sleep debt, and to make up for tiredness, you do intense activity. Too much intellectual or physical activity in the evening can prevent sleep, though.
> Depression. The first sign of depression is often insomnia, which generally occurs at the end of the night (a premature and sudden awakening). In some cases, depression can also cause daytime drowsiness.
> Periods and pregnancy alter the secretion of hormones which act on the body's sleep mechanisms. Pregnant women also have the physical discomfort to contend with over the last few months before giving birth.
> Siestas. If your afternoon nap is too long, it encroaches on your sleep quota for the night.
> A diet that's too rich, fatty or high in protein can also prevent you from getting to sleep, as can drinking caffeine at the end of the day.
> An uncomfortable environment (light, heat, noise, hard mattress).