Schisms

Riker has been waking up exhausted, as though he had only just fallen asleep. As the story progresses, other crew members begin having the same problem. Troi takes Riker, Worf, La Forge, and Kaminer to the holodeck, where the four work together to reconstruct an image from their dreams: a table with a restraint across the torso and a cutting tool on a jointed arm.

Meanwhile, La Forge has come up with a novel way of improving the sensors to speed up charting, by using the warp drive.

It turns out that La Forge's improvement to the sensors has brought them to the attention of beings that live in subspace, who have been abducting them to perform experiments upon them. They attach a tracking device to Riker so that they can find him in subspace after he is abducted, and with it they are able to rescue him and Ensign Sariel Rager.

Notes

The aliens ("Solanagen-based lifeforms", alternatively spelled 'solanogen') from this episode do not appear again in TNG, but do appear in the expanded universe in comics and novels.

The Enterprise crew previously dealt with trouble sleeping in Night Terrors, during which the crew were unable to reach REM sleep. Crusher initially guesses that this is the problem Riker is having.

This episode isn't bad, but the payoff isn't very good. The buildup with Riker's trouble sleeping, the nightmares, and the disappearing crewmen is much more interesting and suspenseful than when they finally reveal that they're being abducted by aliens and send Riker out on the rescue mission.