Sleep quality on trips dramatically affects everything else — energy, mood, enjoyment, immune function. Most hotel rooms have light, noise, or temperature issues that disrupt sleep. Small sleep kit handles 90% of issues.
What to pack
Foam or silicone earplugs. Silk or fabric sleep mask. Melatonin 3-5mg for jet lag (if you tolerate it). Small fan if heat-sensitive (some hotel rooms run hot). Eye drops for dry air. Lavender oil for sleep ritual.
Total kit
Under 200g, fits in toiletry bag. £20-40 to assemble once. Used on most trips for decades.