
Effects of self-selected light-dark cycles and social constraints on human sleep - triplesec
http://www.nature.com/articles/srep45158
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triplesec
Title edited to fit 80char. Original:

'The effects of self-selected light-dark cycles and social constraints on
human sleep and circadian timing: a modeling approach.'

Abstract (TLDR): Why do we go to sleep late and struggle to wake up on time?
Historically, light-dark cycles were dictated by the solar day, but now humans
can extend light exposure by switching on artificial lights. We use a
mathematical model incorporating effects of light, circadian rhythmicity and
sleep homeostasis to provide a quantitative theoretical framework to
understand effects of modern patterns of light consumption on the human
circadian system. The model shows that without artificial light humans wakeup
at dawn. Artificial light delays circadian rhythmicity and preferred sleep
timing and compromises synchronisation to the solar day when wake-times are
not enforced. When wake-times are enforced by social constraints, such as work
or school, artificial light induces a mismatch between sleep timing and
circadian rhythmicity (‘social jet-lag’). The model implies that developmental
changes in sleep homeostasis and circadian amplitude make adolescents
particularly sensitive to effects of light consumption. The model predicts
that ameliorating social jet-lag is more effectively achieved by reducing
evening light consumption than by delaying social constraints, particularly in
individuals with slow circadian clocks or when imposed wake-times occur after
sunrise. These theory-informed predictions may aid design of interventions to
prevent and treat circadian rhythm-sleep disorders and social jet-lag.

