17. Lack of vitamins. Calcium, vitamins D, C and B-complex regulate the nervous system, helping with anxiety.

18. Medicine. Check the labels. Many drugs, from cough syrup to diet pills, contain caffeine and can overstimulate your nervous system if taken before bedtime.

19. Summer. The ideal temperature for sleeping comfort is around 63°F. In winter, lower your thermostat or take a blanket off the bed. In summer, sleep with a fan or the AC on.

20. The neighbor’s dog. Invest on a white noise machine. They are widely available in all price ranges. As a cheap alternative, buy ear plugs or turn a fan on.