light and sound

Power varies by product: many toys use replaceable AA or AAA batteries, some sound machines have built-in rechargeable lithium batteries, others run on AC power, and at least one projector model is USB-powered with no internal battery.

Several units are designed for travel and portability. One model specifically lists a rechargeable battery that lasts up to 15 hours and includes a USB‑C cable. Other listings note built‑in lithium batteries or the option to run via USB power.

Many items include sleep-friendly features such as automatic shut-off or programmable timers, built-in nightlights, and masking-noise functions (white noise or nature sounds). Some all‑in‑one sleep assistants combine several of these features.

Counts vary by model. At least one portable unit lists 10 built‑in sounds; other sleep assistants offer multiple nature and white‑noise options (ocean, rain, wind, stream), though not all listings provide an exact count.

Common inclusions are on‑unit buttons and controls, remote controls, and USB power cables. Some portable sound machines add clip rings or simple physical buttons, and sleep/room assistants may offer smartphone app control and programmable timers.