German researchers have tested how a unique nasal spray affects sleep and memory.
The study involved a nasal spray containing “interleukin-6.” IL-6 is a cytokine; it is a signaling molecule that transmits information between cells.
Seventeen young men spent two nights in a lab, reports a FASEB Journal statement. Each time they read either an emotional or neutral short story. Then they were given either the IL-6 nasal spray or a placebo spray.
Declarative memory was tested in the morning after a night of sleep. Participants wrote down as many words as they could remember from the story.
Results show that IL-6 distinctly improved the sleep-related consolidation of emotional text material; participants who received the dose of IL-6 could remember more words from the emotional story.
The authors report that this type of memory consolidation benefits mostly from sleep in the second half of the night. This is when REM sleep dominates the sleep cycle.
A 2007 study in the journal Sleep found a link between IL-6 and REM sleep; higher IL-6 levels were independently associated with a longer latency to REM sleep.
A study abstract presented at SLEEP 2009 examined sleep and emotional memory; it suggested that sleep preserves in long-term memory only what is emotionally important and relevant to future goals.
The study found that emotional items are selectively remembered both 24 hours and four months later; but these memories are retained only if sleep comes soon after learning.
Learn more about sleep and memory.