0:00:06.463,0:00:08.002
In the late 17th century,

0:00:08.002,0:00:11.762
a medical student named Johannes Hofer[br]noticed a strange illness

0:00:11.762,0:00:15.593
affecting Swiss mercenaries [br]serving abroad.

0:00:15.593,0:00:16.622
Its symptoms,

0:00:16.622,0:00:17.534
including fatigue,

0:00:17.534,0:00:18.573
insomnia,

0:00:18.573,0:00:19.902
irregular heartbeat,

0:00:19.902,0:00:21.223
indigestion,

0:00:21.223,0:00:23.334
and fever were so strong,

0:00:23.334,0:00:26.513
the soldiers often had to be discharged.

0:00:26.513,0:00:30.445
As Hofer discovered, the cause was not[br]some physical disturbance,

0:00:30.445,0:00:34.124
but an intense yearning for their[br]mountain homeland.

0:00:34.124,0:00:36.484
He dubbed the condition nostalgia,

0:00:36.484,0:00:38.633
from the Greek "nostos" for homecoming

0:00:38.633,0:00:41.693
and "algos" for pain or longing.

0:00:41.693,0:00:46.845
At first, nostalgia was considered[br]a particularly Swiss affliction.

0:00:46.845,0:00:51.182
Some doctors proposed that[br]the constant sound of cowbells in the Alps

0:00:51.182,0:00:55.244
caused trauma to the ear drums and brain.

0:00:55.244,0:00:59.763
Commanders even forbade their soldiers[br]from singing traditional Swiss songs

0:00:59.763,0:01:04.034
for fear that they'd lead to desertion[br]or suicide.

0:01:04.034,0:01:09.814
But as migration increased worldwide,[br]nostalgia was observed in various groups.

0:01:09.814,0:01:14.265
It turned out that anyone separated[br]from their native place for a long time

0:01:14.265,0:01:16.815
was vulnerable to nostalgia.

0:01:16.815,0:01:18.505
And by the early 20th century,

0:01:18.505,0:01:22.315
professionals no longer viewed it[br]as a neurological disease,

0:01:22.315,0:01:25.624
but as a mental condition [br]similar to depression.

0:01:25.624,0:01:27.555
Psychologists of the time speculated

0:01:27.555,0:01:31.366
that it represented difficulties[br]letting go of childhood,

0:01:31.366,0:01:35.115
or even a longing to return to one's[br]fetal state.

0:01:35.115,0:01:36.725
But over the next few decades,

0:01:36.725,0:01:40.795
the understanding of nostalgia changed[br]in two important ways.

0:01:40.795,0:01:44.195
Its meaning expanded from indicating[br]homesickness

0:01:44.195,0:01:47.345
to a general longing for the past.

0:01:47.345,0:01:49.297
And rather than an awful disease,

0:01:49.297,0:01:53.585
it began to be seen as a poignant[br]and pleasant experience.

0:01:53.585,0:01:55.575
Perhaps the most famous example of this

0:01:55.575,0:01:59.439
was captured by French author [br]Marcel Proust.

0:01:59.439,0:02:03.446
He described how tasting a madeleine cake[br]he had not eaten since childhood

0:02:03.446,0:02:09.166
triggered a cascade of warm[br]and powerful sensory associations.

0:02:09.166,0:02:14.226
So what caused such a major[br]reversal in our view of nostalgia?

0:02:14.226,0:02:16.445
Part of it has to do with science.

0:02:16.445,0:02:19.756
Psychology shifted away from pure theory

0:02:19.756,0:02:24.516
and towards more careful and systematic[br]empirical observation.

0:02:24.516,0:02:27.906
So professionals realized that many[br]of the negative symptoms

0:02:27.906,0:02:30.677
may have been simply correlated[br]with nostalgia

0:02:30.677,0:02:32.751
rather than caused by it.

0:02:32.751,0:02:36.681
And, in fact, despite being a complex[br]emotional state

0:02:36.681,0:02:39.863
that can include feelings of loss[br]and sadness,

0:02:39.863,0:02:44.322
nostalgia doesn't generally put people[br]in a negative mood.

0:02:44.322,0:02:48.213
Instead, by allowing individuals [br]to remember personally meaningful

0:02:48.213,0:02:51.702
and rewarding experiences[br]they shared with others,

0:02:51.702,0:02:55.042
nostalgia can boost [br]psychological well-being.

0:02:55.042,0:02:58.132
Studies have shown [br]that inducing nostalgia in people

0:02:58.132,0:03:02.652
can help increase their feelings[br]of self-esteem and social belonging,

0:03:02.652,0:03:04.702
encourage psychological growth,

0:03:04.702,0:03:07.839
and even make them act[br]more charitably.

0:03:07.839,0:03:11.033
So rather than being a cause[br]of mental distress,

0:03:11.033,0:03:15.623
nostalgia can be a restorative way[br]of coping with it.

0:03:15.623,0:03:19.143
For instance, when people experience[br]negative emotional states,

0:03:19.143,0:03:23.063
they tend to naturally use nostalgia[br]to reduce distress

0:03:23.063,0:03:25.664
and restore well-being.

0:03:25.664,0:03:28.932
Today, it seems that nostalgia [br]is everywhere,

0:03:28.932,0:03:32.582
partially because advertisers [br]have discovered how powerful it is

0:03:32.582,0:03:34.944
as a marketing technique.

0:03:34.944,0:03:39.001
It's tempting to think of this as a sign[br]of us being stuck in the past,

0:03:39.001,0:03:42.203
but that's not really how nostalgia works.

0:03:42.203,0:03:47.354
Instead, nostalgia helps us remember[br]that our lives can have meaning and value,

0:03:47.354,0:03:50.634
helping us find the confidence[br]and motivation

0:03:50.634,0:03:53.293
to face the challenges of the future.