It has been known for a while that not getting adequate sleep at night can be a risk factor for cancer. It seems that the preponderance of studies suggest that getting at least 6-7 hours of night time sleep is protective against cancer and other diseases such as diabetes, heart disease and obesity. Additionally, new studies have found that getting interrupted sleep is also increases the growth of cancer. Most people notice that they naturally experience different levels of sleepiness and alertness throughout the day, but what causes these patterns? Sleep is regulated by two body systems: sleep/wake homeostasis and the circadian biological clock.
It is hypothesized that this increased risk could be due to lack of light exposure such as short days in winter; night-shift work; jet lag; aging; pregnancy, etc.) Many of these things can disrupt the body’s normal time clock or circadian rhythm.
The International Agency for Research on Cancer (IARC) classified shift work with circadian disruption as a probable human carcinogen (group 2A carcinogen).
Melatonin, a hormone made by the pineal gland in the brain helps control your sleep and wake cycles. It has been proven to have an impressive array of anti-cancer benefits. It not only inhibits the proliferation of a wide range of cancer cell types, it also triggers cancer cell apoptosis (self destruction) and promotes anti-angiogenesis, meaning it prevents the growth of blood vessels that feed the growing tumor.
So, everyone of us should be sleeping in a dark room with very little light. During the night, in the dark, body temperature drops, metabolism slows, and the hormone melatonin rises dramatically. When the sun comes up in the morning, melatonin has already started falling, and you wake up.
Thomas C Erren, Prof. Dr., Puran Falaturi, Prof. Dr., Peter Morfeld, PD Dr., Peter Knauth, Prof. Dr., Russel J Reiter, Prof. Dr., and Claus Piekarski, Prof. Dr., Shift Work and Cancer: The Evidence and the Challenge, Dtsch Arztebl Int. 2010 Sep; 107(38): 657–662.
T.A. LeGates, D.C. Fernandez,and S Hattar., Light as a central modulator of circadian rhythms, sleep and affect. Nat Rev Neurosci. 2014 Jul; 15(7): 443–454.