Can time be slowed in a lucid dream? Lucid dreams allow a person to be conscious while dreaming. It has been reported that it's possible to control various aspects of the dream environment that are not possible during wakefulness, e.g. ability to fly.

Research has shown that the rate of time flow in a dream is same/similar to that of wakefulness. For example, an event that lasts about 5 minutes in a dream, corresponds to about 5 minutes of sleeping. Extending the idea that physically impossible things can be performed during lucid dreams, the question arises whether altering the flow of time, specifically slowing of it, is possible. 

Philosopher Alan Watts has stated that it might be possible to alter the flow of time in a dream: 


  [...] let’s suppose that you were able every night to dream any dream you wanted to dream, and that you could for example have the power within one night to dream 75 years of time, or any length of time you wanted to have. [...] And after several nights of 75 years [...] each [...] 


If such alteration would be possible in a lucid dream, it would suggest the possibility of kind of "mental life extension", where, for example, the person physically lives ~80 years, but mentally, through lucid dreams, experiences the life of hundreds or thousands of years.

Question: Is there anecdotal, or otherwise, evidence or documented past attempts for slowing of perceived passage of time via lucid dreaming?
I'd say yes, in german literature there are some reportings of athelets &quot;training&quot; in slow motion while they are lucid dreaming. I'll try to recap those reportings in english.
Paul Tholey &amp; Kaleb Utecht cite Sadko Günter Solinski, an equestrian, in &quot;Schöpferisch Träumen&quot; (p.257-258):

Als Reiter kann ich somit im Klartraum (A) meine Figuren
zentimetergenau in den Sand (bei der Dressur) bzw. in den Parcours,
z.B. eines Cross-Country hufbreitgenau in die Landschaft zeichnen (bei
der Military). Gelingt mir dies im Zeitlupentempo und verbinde ich (B)
dabei sämtliche (dem Pferd angepassten) ”Hilfen“ im jeweils einzig
richtigen Augenblick einer Bewegungsphase und ”reite ich“ (C) die
Aufgabe so mehrmals (drei- bis neunmal) während eines Klartraums
genau und vollständig durch, so verfügt mein Körper
erfahrungsgemäß am folgenden Tag über genügend ”Körperwissen“, um
den Parcours autonom, d.h. ohne mein bewußtes oder willentliches Zutun
hinter sich zu bringen.

Summary: Solinski claims to able to prepare dressage and eventing very accuratly while lucid dreaming (&quot;im Klartraum&quot;). Sometimes he is able to do this in slow motion (&quot;im Zeitlupentempo&quot;).
The citation can also be found in Daniel Erlacher's PhD thesis (p.62).

Daniel Erlacher has another example in his german PhD thesis on motor learning in lucid dreams. It's about himself training high diving in a lucid dream (above PDF, p.125):

Ein typischer Klartraum in dieser Periode sah etwa wie folgt aus: [...]
Ich versuche, möglichst kunstvoll Salti und Schrauben, oder
Auerbachsalti zu machen. Da das ganze langsam abläuft – wie in
Zeitlupe – habe ich die gute Gelegenheit auf alle Bewegungsabläufe
genau zu achten.

Summary: Erlacher describes one of serveral characteristic lucid treams, where he is trying to do backflips and so on. As everything happens really slowly (&quot;Da das ganze langsam abläuft&quot;) - like in slow motion (&quot;wie in Zeitlupe&quot;) - he is able to focus on every single movement.