etting enough sleep is important for physical and mental health. When I get enough sleep I am more likely to feel energetic and happy. Sleep should be regimented so that there is a predictable schedule. The exact number of hours one ought to sleep is debatable. It seems to be somewhere between seven and nine hours, but until science determines a definitive answer it’s best to find one’s own best answer through experimentation.
I have found that caffeine seems to wreck sound sleep at night for me. If I limit my intake and stop drinking caffeine by lunch time then my system has time to process the caffeine in my body and my chances for a sound sleep are improved, but avoiding caffeinated beverages altogether is best. In my experience caffeine seems to have a cumulative effect if I consume it on consecutive days. A study by Duke University Medical Center published in 2002 showed that the effects of caffeine “are long-lasting and exaggerate the stress response both in terms of the body’s physiological response in blood pressure elevations and stress hormone levels, but it also magnifies a person’s perception of stress.” Another study showed a correlation between stress and insomnia. It is not unreasonable to assume a scientific basis for my perception that cutting caffeine improves sleep.
Botanists and zoologists have long noted 24 hour cycles in animals, plants, fungi, and bacteria. These circadian rhythms are entrained to the environment by external cues called zeitgebers. (Zeitgeber is German for “time giver.”) The zeitgeber used by the human body to synchronize its primary clock to earth days is daylight. Photosensitive ganglion cells in the retina transmit data to the hypothalamus. When these cells detect darkness, the hypothalamus signals the pineal gland on the epithalamus to secrete the hormone melatonin. The upshot is that sunbathing in the morning helps regulate the onset of sleep at night, while bathing in artificial light close to bedtime, as from television and computer screens, may cause insomnia. If you want your circadian rhythms to be in order, it might be wise to expose yourself to daylight when you wake (a brisk walk outdoors, perhaps) and to power down your technology an hour or so before bed (switch from electronic media to reading a book, with a nice cup of chamomile tea sweetened with a touch of honey).
The vitally important habit to adopt in regards to sleep, though, is the most obvious one: calculating a logical bed time and then sticking to it faithfully, in spite of the temptations to stay awake just a little longer and then just a little longer still.
-  See http://www.dukehealth.org/health_library/news/5687 ↩
-  See http://www.psychosomaticmedicine.org/cgi/content/full/62/2/227 ↩
-  See this study: http://www.ncbi.nlm.nih.gov/pubmed/20150866 and this article: http://www.usatoday.com/yourlife/health/medical/2011-03-07-sleep07_ST_N.htm ↩