A study very fancy titled “Attenuation of short wavelengths alters sleep and the ipRGC pupil response” was recently (June 2017) published in OPO.
Luckily, the practical applications of said study are more down to earth: In short, participants were asked to wear blue-light blocking glasses every night before bedtime for 2 weeks. Night-time melatonin-concentration, sleep duration and sleep quality were measured. Subjects wore the glasses 3:57 ±1:03h each night.
Night time melatonin increased from 16.1 ± 7.5 pg mL−1 to 25.5 ± 10.7 pg mL−1 (P < 0.01). Objectively measured sleep duration increased 24 min, from 408.7 ± 44.9 to 431.5 ± 42.9 min (P < 0.001). Mean PSQI score [measures sleep quality] improved from 5.6 ± 2.9 to 3.0 ± 2.2.
Less blue-light before bedtime; better and longer sleep. Good stuff.
The National Sleep Foundation gathered a 18 person- multidisciplinary expert panel to evaluate scientific literature regarding sleep requirements for different age groups. The evaluation is published in the journal “Sleep Health” and nicely illustrated in the infographic below.
Of note, the conclude that individual sleep requirements should be considered, but that these (should) rarely deviate far from the normal range. If done so consistently, over time this will most likely compromise health and well-being.
Alongside the CF-idoms/nonsense-phrases that somehow became popular due to plain stupidity, the “you can sleep when you are old”- phrase should be disregarded and the person stating it publicly ridiculed. That is, of course, only if you are interested in optimising health, memory, mental and physical performance, recovery, lean body mass, pain reduction etc etc.*
* (Thomas et al., 2000; Alhola et al., 2007; Taheri et al., 2004; Knutson et al., 2007; Afflect et al., 1996; Kundermann et al., 2004; Moldofsky et al., 2001)