Could it be healthy for a 16 year old to try out polyphasic sleeping?

Not likely: It isn't recommended. It results in disrupted schedules, usually less total sleeping time, ; of course disrupted sleep. Moreover, our rapid eye movement (rem) sleep cycles approx. Every 90 min., ; so you may lose that pattern. Rem sleep is important ; is linked to consolidation of memory. 16 year olds shouldn't try to substitute "power naps" for good quality sleep. Please refer to a sleep med. Dr.