Can babies have nightmares at 5 months?

[Pheebe]

DS has been a really good sleeper until this week after a bout of gastroeneteritis. He is now waking every 2-3 hours through the night and crying alot. He doesn't seem to be in pain and isn't hungry but sounds like he's genuinely scared, like he's had a bad dream. I know he's developed a bad habit of wanting to sleep on me cos he did last week when he was poorly but this seems to be more than that as he's waking up from sound asleep. Its really upsetting me now as he was soo poorly last week and now this when he's such a little tot.

Hia- I'm convinced that dd started having nightmares when she had her first set of jabs. Until then I hadn't heard her scream in her sleep in the same way as she does sometimes now after those blasted jabs

DS does that sometimes. It's heartbreaking. He's cried in his sleep occasionally too. He also laughs in his sleep and does the 'dream sucking' thing a lot. I think they do dream, they're meant to dream in the womb (though how anyone knows this, I don't know!) and they do have REM sleep when dreams are meant to happen, so I guess that nightmares are part and parcel of that ability.