155. For the purposes of section 16(2)(a) of the 1997 Act, an employer shall carry out, in compliance with section 19 of the Act, a risk assessment, taking account of—

(a) the specific effects and hazards of night work, and

(b) the risks to the safety and health of the employee concerned that attach to the work that a night worker is employed to do,

so as to determine whether that work involves special hazards or a heavy physical or mental strain.