specific characteristics of observers or the sleep deprived peo-
ple they judge.Nevertheless, we believe that the present find-
ings can be generalised to a wide variety of settings, but
further studies will have to investigate the impact on clinical
studies and other social situations.
Importantly, our findings suggest a prominent role
of sleep history in several domains of interpersonal
perception and judgment, in which sleep history has
previously not been considered of importance, such
as in clinical judgment. In addition, because attractive-
ness motivates sexual behaviour, collaboration, and
superior treatment,
13
sleep loss may have conse-
quences in other social contexts. For example, it has
been proposed that facial cues perceived as attractive
are signals of good health and that this recognition has
been selected evolutionarily to guide choice of mate
and successful transmission of genes.
13
The fact that
good sleep supports a healthy look and poor sleep the
reverse may be of particular relevance in the medical
setting, where health estimates are an essential part. It
is possible that people with sleep disturbances, clinical
or otherwise, would be judged as more unhealthy,
whereas thosewho have had an unusually good night’s
sleep may be perceived as rather healthy. Compared
with the sleep deprivation used in the present investi-
gation, further studies are needed to investigate the
effects of less drastic acute reductions of sleep as well
as long term clinical effects.