You will get sick if you go to bed with wet hair in a cold room.

The claim that going to bed with wet hair in a cold room will make you sick can be broken down into two components: first, that wet hair combined with cold conditions causes illness; and second, that this leads to infections like colds or flu. Medical experts and reputable health organizations clarify that viral infections such as the common cold and flu are caused by viruses transmitted through contact with infected individuals or contaminated surfaces, not by exposure to cold temperatures or having wet hair.uhhospitals.orguhhospitals.orgCan You Catch a Cold By Going Outside with Wet Hair?mayoclinichealthsystem.orgmayoclinichealthsystem.orgCan wet hair make you sick?health.clevelandclinic.orghealth.clevelandclinic.orgCan Wet Hair Make You Sick?medanta.orgmedanta.orgCold weather, wet hair and sickness

While being cold or having wet hair might cause discomfort or lower body temperature temporarily, there is no direct causal link to catching a viral illness. Some sources note that cold environments may indirectly increase susceptibility to infections by causing mild immune suppression or by people congregating indoors more often, but wet hair itself is not a risk factor.medicalnewstoday.commedicalnewstoday.comCan wet hair make you sick? Facts, risks, and care tips Anecdotal reports of getting sick after sleeping with wet hair and air conditioningnewsnetwork.mayoclinic.orgnewsnetwork.mayoclinic.orgMayo Clinic Q and A: Myths about catching a cold do not establish causation and may reflect coincidental timing or other factors such as actual viral exposure.

Overall, the scientific consensus is that viruses cause colds and flu, and environmental factors like wet hair in a cold room do not cause these illnesses directly. Therefore, the claim is false as it misattributes the cause of sickness to a non-causal factor.