The International Agency for Research on Cancer concluded in 2007 that shift work involving circadian disruption is probably carcinogenic to humans.

The cycle of sleep is regulated by the body clock. Body clock is located in the brain (suprachiasmatic nucleus). The clock has a period of about 24 hours. During a single day we have a period of 6-10 hours when we are very sleepy. This is the time when we normally sleep. During the remaining 14-18 hours we are usually awake; however, only a portion of that waking time is suitable for intellectual effort. This period of maximum alertness may last as little as 2-6 hours. We should plan our day in such a way that sleep comes at the time of maximum sleepiness, while activities that demand maximum focus or creativity fall into the hours of maximum alertness. It is very difficult and usually very unhealthy to force your body and your body clock to do what you wish. It is far easier to do the opposite: adapt your life to your body clock.

The truth about sleep is simple … if you are feeling sleepy during the day (with the exception of 12-2 hours) most probably you did not got enough sleep! You should forget about those 5-6 hours sleep myths … yes there are some persons (usually old people) who need less sleep but if you are feeling sleepy you did not got enough sleep, and most probably you will need around 8 hours of sleep in a 24 hour period.

Busy people tend to regard sleep as a bank from which time can be borrowed as necessary to allow them to accomplish more by prolonging wakefulness. Thus, a sleep-debt is accumulated over time. If the sleep-debt is not repaid in sleep, per se, some other currency must be used—this usually takes the form of daytime dysfunction and may include cognitive impairment, disordered mood, suboptimal performance, physical fatigue or mental drowsiness (Pilcher and Huffcutt, 1996; Dinges et al., 1997).

Deep sleep coincides with the release of growth hormone in children and young adults. Many of the body’s cells also show increased production and reduced breakdown of proteins during deep sleep. Since proteins are the building blocks needed for cell growth and for repair of damage from factors like stress and ultraviolet rays, deep sleep may truly be “beauty sleep.” Activity in parts of the brain that control emotions, decision-making processes, and social interactions is drastically reduced during deep sleep, suggesting that this type of sleep may help people maintain optimal emotional and social functioning while they are awake.

http://www.benbest.com/health/sleep.html

Adenosine TriPhosphate (ATP) provides the brain with energy, but with increasing wakefulness, adenosine without phosphate accumulates, causing sleepiness. Caffeine blocks adenosine action, reducing sleepiness while also impeding learning and memory [BEHAVIORAL BRAIN RESEARCH; 193:79 (2008)]. Sleepiness — the craving for sleep — can be compared to hunger and thirst. There is a general correlation between the time since last eating, drinking or sleeping and the amount of hunger, thirst or sleepiness. After a certain period of time without sustenance the demands of depravation can become increasingly intense, but these demands can come-and-go. Moments of increasingly distracting discomfort occur with increasing frequency and intensity as the period of depravation increases.

Normal adult volunteers allowed to sleep as much as they wanted (and denied any “distractions”) typically slept 12-16 hours per day initially and between 7.5 to 9 hours per night after about three weeks — an indication that most people have chronic sleep debt.

Sleep deprivation in rats compromises the immune system, allowing bacterial overgrowth to cause fatal septicemia [AMERICAN JOURNAL OF PHYSIOLOGY; Everson,CA; 278(4):R905-R916 (2000)]. Sleep deprivation in rats causes an increase in leukocytosis & inflammatory cytokines, which can be quickly reversed by sleep [AMERICAN JOURNAL OF PHYSIOLOGY; Everson,CA; 289(4):R1054-R0163 (2005)]. In healthy volunteers, sleep deprivation increased the level of pro-inflammatory C-reactive protein in a linear, dose-dependent manner [JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY; Meier-Ewert,HK; 43(4):678-683 (2004)].

The accumulation of adenosine during waking periods is thus associated with the depletion of the ATP reserves stored as glycogen in the brain. The increased adenosine levels trigger non-REM sleep, during which the brain is less active, thus placing it in a recovery phase that is absolutely essential—among other things, to let it rebuild its stores of glycogen.

https://en.wikipedia.org/wiki/Adenosine#Metabolism
When adenosine enters the circulation, it is broken down by adenosine deaminase, which is present in red cells and the vessel wall.
Adenosine deaminase deficiency is a known cause of immunodeficiency. (not enough … = immunodeficiency, … too much anemia, ADA2 is the predominant form present in human blood plasma and is increased in many diseases, particularly those associated with the immune system: for example rheumatoid arthritis, psoriasis, and sarcoidosis. The plasma ADA2 isoform is also increased in most cancers. )

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769007/
Conversely, Ado receptor antagonists increase wakefulness and decrease sleep [61, 72, 75]. One of the most commonly used pharmacological agents, caffeine, is a nonselective Ado antagonist which primarily acts at two of the four Ado receptor subtypes, the A1R and A2aR to influence sleep/waking behavior.

http://biology.stackexchange.com/questions/7673/what-causes-adenosine-build-up-in-the-brain-when-awake
So we can just trick the brain to sleep less …
http://dmm.biologists.org/content/3/11-12/773

Still sleepy? Perk up with these 10 energy-boosters
http://www.today.com/health/still-sleepy-perk-these-10-energy-boosters-1C6608998

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3963479/
https://www.supermemo.com/articles/sleepchart.htm
https://www.supermemo.com/en/articles/polyphasic
https://www.supermemo.com/articles/sleepchart.htm
https://www.hindawi.com/journals/ije/2010/270832/
http://brain.oxfordjournals.org/content/124/8/1482
http://thebrain.mcgill.ca/flash/a/a_11/a_11_m/a_11_m_cyc/a_11_m_cyc.html

All about balance?
https://en.wikipedia.org/wiki/Adenosine_deaminase
https://en.wikipedia.org/wiki/Adenosine_deaminase_deficiency
https://books.google.com/books?id=2TDrBwAAQBAJ&pg=PA64&lpg=PA64&dq=increase+adenosine+deaminase+sleep&source=bl&ots=uZZirqEnd0&sig=V0_-fo1tfdLjGDZng6cRgREP8WU&hl=en&sa=X&ved=0ahUKEwji-pbH1fPPAhXI7xQKHR61D0Q4ChDoAQhUMAk#v=onepage&q=increase%20adenosine%20deaminase%20sleep&f=false
https://books.google.com/books?id=ODntNk2ySO8C&pg=PA195&lpg=PA195&dq=adenosine+deaminase++increase&source=bl&ots=sYKUwjPFXA&sig=sTzHZkMWvjalaH8k_RLT5CAw-kE&hl=en&sa=X&ved=0ahUKEwie7ajk3PPPAhXDXRQKHaeIDqQ4KBDoAQg9MAU#v=onepage&q=adenosine%20deaminase%20%20increase&f=false
http://www.brainprotips.com/how-coffee-affects-the-brain/
http://www.auditor.sro.org/pdf/2479.pdf
http://www.bionews.org.uk/page_46812.asp
https://en.wikipedia.org/wiki/Adenosine_monophosphate_deaminase_deficiency_type_1
http://journal.frontiersin.org/article/10.3389/fneur.2012.00062/full
http://searchinghowtosleepbetter.com/category/uncategorized/

To be honest the only thing which can give us more time is a 4 hours sleep a week by Timothy Ferriss‎.

 

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